Chordate Biology (Complete slide) - PDF

ABCS 341 (COMPARATIVE CHORDATE BIOLOGY) INTRODUCTORY LECTURE Prof. Daniel K. ATTUQUAYEFIO Department of Animal Biology & Conservation Science (DABCS) University of Ghana, Legon  CLASSIFICATION AND NOMENCLATURE WHY CLASSIFY? – A...

ABCS 341 (COMPARATIVE CHORDATE BIOLOGY) INTRODUCTORY LECTURE Prof. Daniel K. ATTUQUAYEFIO Department of Animal Biology & Conservation Science (DABCS) University of Ghana, Legon  CLASSIFICATION AND NOMENCLATURE WHY CLASSIFY? – Animals are related to one another and can be categorized into various groups based on similarities of ancestry, morphology, etc. – Classification helps us to generalise or specialise as appropriate (e.g. knowledge about one entity presumes knowledge about other entities closely- related to it) – Classification is the most powerful information retrieval and organising system of the biological sciences (e.g. a surgeon has to use classification to generalise on the organs to be found in the body (e.g. position of the heart) – A standardized classification system enables comparison and communication of research results worldwide  CLASSIFICATION (2) RULES Taxonomic rules recognise seven major classification levels or taxa in a heirarchy: – KINGDOM (Animalia) → PHYLUM (Chordata) → CLASS (Mammalia) → ORDER (Primates) → FAMILY Pongidae) → GENUS (Homo) → SPECIES (Homo sapiens) Sub-levels (prefixes) are sometimes added to main levels in advanced zoological studies to include more or less (e.g. “super-”, “sub-”, or “infra-”) Sometimes new levels are inserted altogether (e.g. “branch”, “tribe” or “cohort”) As a general rule, family names end in “-idae”, superfamily names end in “- oidea”, and subfamily names end in “-inae”  NOMENCLATURE WHY STANDARDIZE NOMENCLATURE? – Common names of animals may differ locally – In scientific work, it is necessary to make comparisons and to communicate results so animals must have one universally-accepted scientific name (e.g. a lion is always referred to as Panthera leo) – Some common names do not provide clues as to the type of animal: John Dory (Zeus faber) ………………… Bony fish Prairie dog (Cynomys parvidens) ………… Squirrel Water moccasin (Ancistrodon piscivorus) …… Snake Fer-de-lance (Bothrops atrox) ……………… Snake Jellyfish (Aurelia aurita) ………………… Invertebrate Hellbender (Cryptobranchus alleganiensis) Salamander  NOMENCLATURE (2) INTERNATIONAL CODE OF ZOOLOGICAL NOMENCLATURE (ICZN) Document ratified in Berlin in 1901, containing 88 articles and 338 pages Ensures that all zoologists recognise only one scientific name for a particular species to avoid confusion Promotes stability in animal scientific names: new findings sometimes require that the scientific names have to be changed from time to time The ICZN ratifies any new animal scientific name changes to ensure universal acceptance, and its authority is final (e.g. Lion) – Old name: Felis leo – New name: Panthera leo  NOMENCLATURE (3) SOME ICZN RULES Scientific names must follow the binomial system used by Carl Linne (Carolus Linnaeus) in 1758 The scientific name of every animal species should be a Latin binomen (two-part name), comprising of a generic name and a specific name The generic name is always initially capitalised, while the specific name is not (e.g. Homo sapiens, Panthera leo) The binomen must always be italicized or underlined The first person naming a new species or taxon is required to provide its description It is customary to add the name of the person who first described a species using a binomen (e.g. Picus principalis Linne) A trinomen (3-part name) is used when a subspecies is being named (e.g. Loxodonta africana africana or L. a. cyclotis)  CHORDATES Phylum: CHORDATA – Made up of: – PROTOCHORDATES (primitive, mainly marine animals lacking vertebral column but possessing a persistent notochord – VERTEBRATES (animals with a vertebral column developed from the primitive notochord)  CHORDATES (2) WHY PHYLUM CHORDATA? Lamarck (1744-1829) divided all living things into two major groups: – Vertebrates: Animals with backbones- VERTEBRATA – Invertebrates: Animals without backbones- INVERTEBRATA Some primitive, mainly marine animals (Protochordates) lacked a vertebral column, but were otherwise more similar to the vertebrates than the invertebrates It was thus necessary to have a larger group (phylum), CHORDATA, to include the Protochordates and the true Vertebrates (animals with a vertebral column developed from the primitive notochord)  CHORDATES GENERAL CHARACTERISTICS Notochord, later to be replaced by the vertebral column in vertebrates, but retained in protochordates Visceral clefts (pharyngeal gill structures), for sifting food particles from water or respiration and become vascular gills in fishes and larval amphibians, but disappear in adult terrestrial vertebrates Dorsal hollow nerve cord- future brain and spinal cord in vertebrates True, metamerically-segmented post-anal tail Ventral heart with highly-organised closed blood vascular system Bilateral symmetry Well-developed head  CHORDATES SYSTEMATICS Phylum: CHORDATA Subphylum: ACRANIA (Protochordates) Class: UROCHORDATA Class: CEPHALOCHORDATA Subphylum: CRANIATA (VERTEBRATA) (Vertebrates) Superclass: AGNATHA (Jawless Vertebrates) Superclass: GNATHOSTOMATA (Jawed Vertebrates) Class: OSTEICHTHYES (Bony Fishes) Class: CHONDRICHTHYES (Cartilaginous Fishes) Class: AMPHIBIA (Amphibians) Class: REPTILIA (Reptiles) Class: AVES (Birds) Class: MAMMALIA (Mammals)  PROTOCHORDATES The group “Protochordates” comprises of two subphyla: Subphylum: Urochordata Subphylum: Cephalochordata  UROCHORDATA Sea Squirt CEPHALOCHORDATA Amphioxus  SYSTEMATICS AGNATHA Sucking mouth (buccal chamber) Single median nostril Well-formed eyes Lamprey No paired appendages Lampreys and hagfishes Hagfish  SYSTEMATICS CHONDRICHTHYES Cartilaginous skeleton Ventral mouth Heterocercal tail Shark Exposed gill slits; no operculum Intromittent organs (claspers- male pelvic fins) Sharks, rays and skates Ray  SYSTEMATICS OSTEICHTHYES Largest vertebrate class Bony skeleton Homocercal tail Sergeant-Major Operculum present Paired fins Teleosts, lungfishes, lobefins Tilapia  SYSTEMATICS AMPHIBIA First tetrapods Indirect development (metamorphosis) Soft, scale-less glandular skins Respiration- buccal, cutaneous, pharyngeal, pulmonary Three-chambered hearts Frogs, toads, salamanders, newts, caecilians  SYSTEMATICS AMPHIBIA Toad Frog Arrow-poison Frog Flying Frog Caecilian  SYSTEMATICS REPTILIA First true terrestrial vertebrates Direct development Dry, scaly skins Shelled eggs Internal fertilization; intromittent organ Oviparity; ovoviviparity Chelonians, snakes, lizards, crocodiles, amphisbaenians  SYSTEMATICS REPTILIA Pelomedusa subrufa (Marsh Terrapin) Agama agama (Rainbow Lizard) Python regius Royal Python) Crocodylus niloticus (Nile Crocodile) Bitis arietans (Puff Adder)  SYSTEMATICS REPTILIA Mabuya quinquetaeniata Chamaeleo gracilis Five-lined Skink) (Gracile Chameleon) Varanus komodoensis Trachylepis perottettii (Komodo Dragon) (Orange-flanked skink)  SYSTEMATICS REPTILIA Eunectes murinus Heloderma suspectum (Anaconda) (Gila Monster) Python reticulatus (Reticulated Python)  SYSTEMATICS AVES Feathers on skin Forelimbs modified into wings for flight Toothless; presence of bill/beak Homeothermic Four-chambered heart Pneumatic bones; air-sac system Ostriches, penguins, hawks, guinea-fowls  SYSTEMATICS AVES Penguin Vulture  SYSTEMATICS MAMMALIA Hair on skin Mammary glands Pangolin Sweat glands Heterodont dentition Bat Homeothermic Four-chambered heart Examples: Duck-billed platypus, kangaroo, shrew, rodent, elephant, buffalo, leopard, pangolin  SYSTEMATICS MAMMALIA Elephant Antelope Hippopotamus Giraffe Rodent  ABCS 341 (COMPARATIVE CHORDATE BIOLOGY) PROTOCHORDATES AND FISHES Prof. Daniel K. ATTUQUAYEFIO Department of Animal Biology & Conservation Science (DABCS) University of Ghana, Legon 1  INTRODUCTION Of the more than 65,000 living species of chordates, about half are bony fishes (Class: Osteichthyes) The phylum Chordata includes the following subphyla: – Tunicata (Salps and sea squirts) – Cephalochordata (Lancelets) – Vertebrata (Fishes, amphibians, reptiles, birds, and mammals) The first two subphyla are together known as the Protochordates (primitive chordates), and all the other chordates belonging to the Vertebrata are the Euchordates (modern chordates). 2  INTRODUCTION (2) Six criteria used to determine the evolutionary branch of vertebrates – Agnatha (Cyclostomes): Absence of mandibles (jaws) separates from other vertebrates – Pisces (Fishes): Absence of limbs (possess fins) separates them from Tetrapods (terrestrial vertebrates) – Chondrichthyes (Cartilaginous fish): Absence of bony (osseous) skeleton separates them from Osteichthyes (bony fish) – Amphibia: Absence of waterproof skin separates from other terrestrial vertebrates – Reptilia: Absence of warm blood (homeothermy) separates from Birds and Mammals – Aves (Birds): Absence of mammary glands and hair separates from Mammals 3  PROTOCHORDATES SYSTEMATICS Phylum: CHORDATA Subphylum: UROCHORDATA (TUNICATA) – Tunicates (3,000 sp.) (Marine; adults sessile, occasionally planktonic and enclosed in a tunic containing cellulose) Subphylum: CEPHALOCHORDATA (ACRANIATA) – Lancelets (30 sp.) (Body laterally-compressed, transparent; fish-like, chordate characteristics persist throughout life) 4  Subphylum: UROCHORDATA (TUNICATA) TUNICATES About 2,150 species of marine chordates, occurring mostly in shallow water Occur in a range of solid or translucent colours, resembling seeds, grapes, peaches, barrels, or bottles. Adult body quite simple, being essentially sac-like with two siphons through which water enters and exits. Free-living larvae and sessile or colonial adults, with young larvae being called tadpoles Larvae exhibit all chordate characteristics: notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail 5  Subphylum: UROCHORDATA TUNICATES Some tunicates live in a secreted cloak or “tunic”, containing a cellulose- like substance (tunicin) for support About 1,400 species, occurring in water less than 100m deep. 3 classes: Ascidiacea (sea squirts), Larvacea (Appendicularia) and Thaliacea (salps) Adults not chordate-like; notochord disappears during metamorphosis (or confined to the tail), without segmentation in the adult. Most adults sessile, being permanently attached to rocks or other hard surfaces on the ocean floor Acoelomate, with no sign of metamerism in both the larva and adult. 6  TUNICATES Sea Squirt 7  Subphylum CEPHALOCHORDATA LANCELETS About 30 species of fish-like protochordates ( to 10 cm long) in tropical and temperate coastal waters, often buried tail downward in sand Body with three openings: mouth, guarded by tentacles called buccal cirri and through which water enters; atriopore towards the posterior (tail) end of the animal through which water exits; anus through which waste products exit. Enormous pharyngeal gill basket occupies most of the body within the atrial cavity, resulting in reduced swimming muscles (poor swimmers) As adults, exhibit all four basic characteristics of the phylum Chordata: dorsal nerve cord, notochord, post anal tail, pharyngeal gill slits (very primitive example of the basic Chordate plan) No central heart; colourless blood lacks haemoglobin 8 Subphylum CEPHALOCHORDATA (2) Closed blood system; main ventral and paired dorsal aorta connected by an intermeshing series of smaller vessels; both cutaneous and branchial oxygenation. No brain or cranium like in the Vertebrata Protonephridia collect fluid from small coelomic sacs at the top of the gills, and pass urine into the atrium There is no brain or anterior sense organ Fertilization external; cleavage holoblastic and radial Larva is free-swimming and ciliated Sexes separate; fertilization external e.g. Branchiostoma lanceolatum (Lancelet) 9 Subphylum CEPHALOCHORDATA (5) 10  Subphylum VERTEBRATA (CRANIATA) Body consisting of an anterior head (with brain), middle trunk, and posterior (post-anal) tail Appendages: consist of fins in fishes, and jointed limbs in tetrapods, variously modified for use in different environments (e.g. flippers in whales, and wings in birds and bats). Bilateral symmetry Some paired structures not always of the same size (e.g. liver, lungs, reproductive organs) or may be shifted in position (e.g. kidneys) Vertebral column a rigid supporting bony or cartilaginous structure which replaces the notochord of the chordates, the first skeletal structure to appear in vertebrate embryos. 11  Subphylum VERTEBRATA (2) Possession of an anterior head (housing the brain), middle trunk, (containing the body cavity- coelom enclosed in a body wall- peritonium- and posterior (post-anal) tail There are fins in fishes, and jointed limbs in tetrapods, which have been variously modified for use in different environments (e.g. flippers in whales, and wings in birds and bats). Three principal body axes: – Antero-posterior: Longitudinal axis (front to back or top to down, depending on posture) – Dorso-ventral: – Left-right: Bilateral symmetry Some of the paired structures may not always be of the same size (e.g. liver, lungs, reproductive organs) or may be shifted in position (e.g. kidneys) 12  Subphylum VERTEBRATA (3) Vertebral column is a rigid supporting bony or cartilaginous structure which replaces the notochord of the chordates, the first skeletal structure to appear in vertebrate embryos Pharynx represented by pouches or slits near the anterior end of the body in the vertebrate embryo, which later develops into gills in aquatic vertebrates, and may close in terrestrial vertebrates Nervous system is dorsal and hollow or tubular, comprising of the central nervous system (CNS) and autonomic nervous system (ANS) Endoskeleton is made up of cartilage and/or bone, with a vertebral column, cranium, limb girdles, and two pairs of jointed appendages which are variously modified in different groups 13  Subphylum VERTEBRATA (4) The skin has an outer epidermis (cuticle) and an inner dermis. Skin structures like feathers, hair, horns, glands, hooves, claws, nails, etc. are ectodermal in origin Teeth, bony scales, abdominal ribs, etc. are mesodermal (dermis) in origin Apart from gills and lungs, there are also cutaneous, buccopharyngeal, and extra-embryonic respiration Vertebrate evolution involved a transition from gills to lungs, but swimbladders recur in bony fishes, largely for buoyancy rather than respiration. Lungfishes however have the swimbladder modified into a lung 14  Subphylum VERTEBRATA (5) Complete digestive system (alimentary canal) ventral to the spinal column with specialised regions for: - acquisition (ingestion) , - processing (oral cavity, pharynx, oesophagus) - temporary storage (stomach) - digestion and absorption (duodenum, ileum, caecum, colon, rectum) - disposal (anus, cloaca) Alimentary diverticulae include the liver, pancreas, and caeca Chief excretory organs are the kidneys (nephroi), absent in most marine or desert animals. Degree of complexity dependent on level of evolution Bladder may be present or absent 15  Subphylum VERTEBRATA (6) Closed system of circulation with haemoglobin confined to erythrocytes (red blood cells) Single ventral multi-chambered heart All vertebrates are dioecious (separate sexes) Fertilization is mainly external in aquatic and semi-aquatic forms (fishes, amphibians), and internal in the terrestrial forms (reptiles, birds, mammals) Vertebrates are either: – oviparous (egg-laying) – ovoviviparous (egg retained in body until hatching, but not dependent on female for nourishment) – viviparous (young develop in female’s uterus and nourished by a placenta 16  FISHES GENERAL Gill-bearing aquatic craniates lacking limbs with digits Includes the agnatha (lampreys and hagfishes), cartilaginous fishes (sharks, rays and skates) and bony fishes (lungfishes, teleosts) Most ectothermic ("cold-blooded"), with body temperatures varying with ambient temperatures Occur in nearly all aquatic environments, from high mountain streams to the deepest oceans 33,600 described species, exhibiting greater species diversity than any other group of vertebrates 17  FISHES CLASSIFICATION Phylum CHORDATA Superclass AGNATHA (Jawless vertebrates) Class MYXINI (Hagfishes) Class PETROMYZONTIDAE (Lampreys) Superclass: GNATHOSTOMATA (Jawed vertebrates) Class: CHONDRICHTHYES (Cartilaginous fishes) Subclass: HOLOCEPHALI (Chimaeras, ratfishes) Subclass: ELASMOBRANCHII (Sharks, rays, skates) Order: PLEUROTREMATA (Sharks) Order: HYPOTREMATA (Rays, skates, sawfishes) 18  FISHES CLASSIFICATION (2) Class: OSTEICHTHYES (Bony fishes; 3 subclasses) Subclass: CROSSOPTERYGII (Lobe-finned fishes) Subclass: DIPNEUSTI (DIPNOI) (Lungfishes) Subclass: ACTINOPTERYGII (Ray-finned fishes) 19  Class AGNATHA JAWLESS FISHES Distinguished from all other vertebrates (Gnathostomata) by their lack of true jaws. About 50 species, constituting only about 0.2% of all living fish species Two main orders: Petromyzoniformes (Lampreys) and Myxiniformes (Hagfishes) There are both marine and freshwater lampreys, some of which are anadromous (marine, but migrate to freshwater to spawn) Hagfishes are all benthic marine organisms Adult lampreys measure 1 metre long and weigh 2.5 kg. Hagfishes measure 0.9 metres (max) 20  AGNATHA (2) GENERAL CHARACTERISTICS Absence of well-developed paired appendages, cylindrical, eel-shaped (up to 1 m in length) Sucking mouths without jaws, and a single median nostril Primitive vertebral column with notochord covered or not covered by incipient neural arches (cartilaginous skeleton) Dorsal fin small or missing, but undivided if present Most are “parasitic”, attaching themselves to fishes and other aquatic animals and rasping their flesh; attachment may last or several days, and the prey eventually dies External fertilization; single gonad without a duct Two subclasses: Cephlaspidomorpha (Monorhina), the lampreys, and the Myxini, the hagfishes. 21  AGNATHA (3) Lamprey Hagfish 22  LAMPREYS Vrs. HAGFISHES Feature Lamprey Hagfish Habitat Marine, freshwater Marine Habit Parasitic, non-parasitic Parasitic Feeding Sucks out host fish blood Scavenger; dead fish Breeding Anadromous (marine to FW) Sea floor spawning Body Stout Feeble Size Up to 1 metre Under 1 metre Dorsal fins 2 1 or absent Skin Less slimy More slimy Eyes Paired and functional Paired and degenerate Mouth Ventral Terminal Buccal funnel Present Absent Tongue Less developed; larger teeth More dveloped; smaller teeth 23  LAMPREYS vrs. HAGFISHES Feature Lamprey Hagfish Salivary glands Present; anticoagulant Absent External gill slits 7 pairs 1 pair Brain Better developed Poorly developed Cranial nerves 10 pairs 8 pairs Reproduction Separate sexes; unisexual Hermaphrodite; bisexual Development Indirect; larval stage Direct; no larval stage 24  Class CHONDRICHTHYES CARTILAGINOUS FISHES There are two classes of fishes: » Chondrichthyes (cartilaginous fishes) » Osteichthyes (bony fishes) About 800 living species of cartilaginous fishes world wide, constituting about 2.5% of all known fish species Skeletons made of cartilage, heterocercal tails Most are marine predators, but a few occur in brackish and freshwater lakes and rivers Largest living vertebrates apart from the whales World’s largest cartilaginous fish (and also the largest known fish) is the whale shark (Rhincodon typus), measuring up to 18 m long Smallest shark is Squaliolus laticaudus, measuring 15 cm long. 25 SHARK 26  CHONDRICHTHYES GENERAL CHARACTERISTICS Endoskeleton entirely cartilaginous Heterocercal tail (caudal fin) with large dorsal lobe (flange), into which the distal end of the axial skeleton extends, and a smaller ventral flange Absence of swimbladder or lung 5-7 exposed gill clefts; no operculum present Mouth ventral Paired pectoral and pelvic fins; two dorsal median fins usually, but few have only one; single anal fin; male pelvic fins modified into “claspers” (for internal fertilization) 27  GENERAL CHARACTERISTICS (2) Streamlined (fusiform) body for least drag per given volume and velocity (length = 4 x maximum diameter) Digestive system with J-shaped stomach, liver, gall bladder, and pancreas present Sexes separate; paired gonads; cloaca present; ovi-, ovovivi-, and viviparity; direct development Two subclasses: Elasmobranchii (sharks, rays and skates) and Holocephali (ratfishes and chimaeras) Two orders of Elamobranchii: Selachii (Lamniformes) (sharks, dogfishes) and Batoidea (Rajiformes) (rays, skates) 28  Subclass ELASMOBRANCHII Order SELACHII (SHARKS) Fusiform body shape; 7 lateral gill slits on each side of neck Carnivorous, tracking prey using a lateral line system and large olfactory organs Spiracle (modified gill slit) behind eye; vision not well-developed Free pectoral fins (i.e. unattached to head) Well-developed muscular tail with large heterocercal caudal fin Fertilization internal, some viviparous with up to two-year gestation periods Some are very dangerous to humans (great white shark - Carcharodon spp., hammerhead shark - Galeocerdo spp.) Useful as food and for leather 29  Order BATOIDEA (RAJIFORMES) RAYS AND SKATES Specialised for bottom-dwelling, with greatly-enlarged pectoral fins fused to the head and used like wings for swimming Body dorso-ventrally flattened; pelvic fins are much smaller, and anal fins are absent Gill openings and mouth on the underside of the head, and spiracles are on the dorsal side behind the eyes, an arrangement ensuring inhalation through the spiracles to prevent clogging of the delicate gill filaments since the mouth is often buried in sand Teeth small and blunt, arranged pavement-like with several rows in use at once, an adaptation for crushing their prey (molluscs, crustaceans, sea urchins, etc.) 30  RAYS AND SKATES (2) Sting rays (Dasyatis spp.) have a slender and whip-like tail armed with one or more saw-like spines with venom glands at the base. Electric rays (Torpedo spp.) possess large electric organs on each side of the head, producing high amperage current to stun prey or discourage predators Rays and skates differ form the sharks in the following major ways: – Dorsoventrally-flattened bodies – Large spiracles behind the eyes dorsally – Five pairs of ventral gill slits – Enlarged pectoral fins joined along the sides of the head – Reduced whip-like tail 31 RAY 32  Subclass HOLOCEPHALI RATFISHES AND CHIMAERAS Chimaeras possess a mixture of shark- and bony fish-like features, with about 25 living species worldwide General features are as follows: – Blunt-faced, with large eyes and terminal mouths – Body not dorso-ventrally flattened; slender tapering tail – Jaws bear large, flat plates instead of a toothed mouth with the upper jaw completely fused to the cranium (unusual in fishes!) – No spiracles or cloaca; body scaleless as adults – Poison spine on the first dorsal fin; fleshy operculum present – Forehead equipped with hook-like clasper used to hold the female during copulation, but actual copulation achieved with pelvic claspers – Feed on seaweed, molluscs, echinoderms, crustaceans and fishes 33 CHIMAERA 34  HUMANS AND CHONDRICHYHYES Beneficial. – Food sources (sharks and rays) in some areas (e.g. Asia, California, etc.) – Shark skin is used for a variety of products (e.g. casing books, jewel boxes, sword handles; polishing wood, ivory; leather) – Shark liver contains oil which is rich in vitamin A (popular in Scandinavia and Greenland) 35  HUMANS AND CHONDRICHTHYES Detrimental Sharks are a nuisance to fishermen and anglers by tearing fishing nets to steal netted fishes, or by removing bait or fishes from hooks Large species may capsize small boats and injure or kill fishermen in the process Tropical and subtropical species are a serious menace to bathers Some sharks specialise in atacking human swimmers or victims of marine or aerial accidents (shipwrecks, plane crashes, etc.); examples of such man- attacking sharks are the great white shark (Carcharodon carcharias), hammerhead sharks, etc. The spines of sting rays can kill or injure humans 36  Class OSTEICHTHYES BONY FISHES About 22,000 species of bony fishes worldwide; there are more fishes in the world than any other groups of vertebrates, both in abundance and diversity (80% of the earth’s surface is covered by water. Bony fishes have invaded every hospitable aquatic habitat, an example of adaptive radiation The smallest known bony fish: Marshall Islands goby (Pandaka pygmaea) of the Philippines (14 mm long) Majority of bony fishes marine, but about 7,000 freshwater species Body form related to habitats and feeding habits: – Predaceous pelagic fish: Trim, elongate bodies, powerful tail fins, etc., for swift movement in water – Bottom-feeding fish: Flattened bodies for movement and concealment on the ocean floor 37  Class OSTEICHTHYES GENERAL CHARACTERISTICS Skeleton more-or-less bony, either in the dermis or endoskeleton; numerous vertebrae; notochord may persist in part Scales may be ganoid, cycloid, or ctenoid (overlapping shingle-like), never placoid Respiration by gills covered by a common operculum of bony plates Both median and paired fins with cartilaginous or bony fin rays Body usually laterally compressed, with transvers axis shorter than dorso- ventral axis Tail typically homocercal (upper and lower lobes of equal size); vertebral column rarely extending into caudal fin Mouth usually terminal 38  GENERAL CHARACTERISTICS (2) Swimbladder often present as buoyancy organ or lung, with or without duct connected to pharynx Some toothless; jaws present; nostrils located dorsally on snout Stomach may be J-shaped; most have numerous (up to 200) slender diverticula (pyloric caeca) opening into intestine just beyond the pyloric sphincter Intestine long and coiled, with no spiral valve (except in lungfishes) Two-chambered heart, with arterial and venous systems; blood containing nucleated erythrocytes Sexes separate; fertilization external (no claspers); few viviparous; eggs small and not laid in horny case; larval forms differ greatly from adults 39 BONY FISH 40  Subclass CROSSOPTERYGII LOBE-FINNED FISHES Paired lobed fins bear a sharp resemblance to tetrapod limb; nostrils (choanae) open into the mouth, gills and lungs for respiration Very important in vertebrate evolution; gave rise to the Amphibia, and later all tetrapod vertebrates Diphycercal (three-pronged) tail; more cartilaginous parts than other bony fishes Calcified or vestigeal swimbladder Only surviving species: coelacanth (Latimeria chalumnae) named after a South African Museum director, M. Courtney-Latimer Thought to have gone extinct 70 million years ago, but the remains of one found off coast of South Africa in 1938; caught occasionally by fishermen in the Comoros (near Madagascar) during deep sea fishing 41 LOBE-FINNED FISHES (2) Latimeria (Coelacanth) 42  COELACANTH The coelacanth was discovered off the coast of South Africa in 1938, some 66 million years after it was thought to have gone extinct There are currently less than 10,000 of the two species still in existence, with numbers continually dwindling, due to their getting caught up in fishing nets, as well as the effects of climate change They grow up to 2 meters in length, weigh up to 100kg, and live around 60 years in the wild 43  Subclass DIPNEUSTI (DIPNOI) LUNGFISHES Resemble the lobe-finned fishes in having lobate paired fins and lungs Represented by only three living species: – Neoceratodus (Australian lungfish): Least specialised of the lungfishes; able to withstand stagnant oxygen-poor water by coming to the surface to gulp air into its single lung; cannot however live out of water – Protopterus (African lungfish) – Lepidosiren (South American lungfish) Both the latter two lungfishes can live out of water for a long time 44  LUNGFISHES Considered to be among the most primitive living fishes Three families: Protopteridae (African lungfishes), Ceratodontidae (Australian lungfishes) and Lepidosirenidae (South American lungfishes) Members of this group possess 1 or 2 lungs for breathing atmospheric oxygen Young lungfishes possess external gills, which are lost (in most species) as the fish develops As lungfish develop from juveniles to adults, their teeth fuse together to form tooth plates which they use to chew their food (all lungfishes are omnivorous). 45 Protopterus (African Lungfish) 46  Subclass ACTINOPTERYGII RAY-FINNED FISHES The subclass Actinopterygii comprises some 27,000 species of ray-finned bony fishes Includes the modern rayfins Teleostei 47  TELEOSTEI MODERN RAYFINS Almost completely ossified internal skeleton Light, thin and flexible cycloid or ctenoid scales Homocercal tails Swimbladders for buoyancy 48 FISH ANATOMY 49  HUMANS AND OSTEICHTHYES Source of protein since historical times Fishery industry provides employment for people Fish oil is used in the manufacture of paints and insecticidal sprays, as well as containing vitamin D (e.g. cod liver oil) Discards from fish canneries provide fish meal for the poultry and fertilizer industry Heads and trimmings from fish are used in the manufacture of liquid glues Sport fishing is an important source of food as well as recreation Aquaria and aquaculture ponds provide sources of food, entertainment, education, aesthetics, research, etc. Fishes are important in the biological control of insects (e.g. some fishes like the cichlids feed on mosquito larvae, thereby controlling their populations 50  ABCS 341 AMPHIBIANS Prof. DANIEL K. ATTUQUAYEFIO Department of Animal Biology & Conservation Science (DABCS) University of Ghana, Legon  INTRODUCTION First vertebrates to adapt to terrestrial life (first tetrapods- paired limbs with digits instead of fins) Cold-blooded (ectothermic) vertebrates Formerly referred to animals that could live both on land and in water, but now restricted to the taxon Amphibia (anurans, urodelans and caecilians) Dependence on water for part of life-cycle (“double life”)- “amphi” = double; “bios” = life About 3,500 species worldwide Largest amphibian: Megalobatrachus maximus (Giant Salamander)- 1.6 m; 10 kg Smallest amphibian: Sminthillus [Eleutherodactylus] limbatus (Cuban Dwarf Frog)- 1.0 cm Paedophryne amauensis (Papua New Guinea Dwarf Frog)- 0.77 cm Largest anuran: Conraua goliath (Cameroon Goliath Frog)- 33 cm; 3.5 kg  GENERAL FEATURES Shell-less eggs, which must be laid in water or humid environments- Indirect development (metamorphosis): Early stages of life-cycle aquatic with gilled, larval forms which later metamorphose into lung-breathing terrestrial adults External fertilization (pseudocopulation, amplexus, oviparity- egg- laying) Three-chambered heart (two auricles, one ventricle) Pentadactyl (five-toed) limbs; number of toes frequently reduced. Ectothermic (“cold-blooded): depend largely on behavioural means to regulate their body temperature (like fishes and reptiles) Pulmonary (lung), branchial (gill), cutaneous (skin) and buccal (mouth lining) respiration Soft, smooth, scale-less glandular skin (with poison glands, pigment cells)- skin usually moist with mucous glands and scales generally lacking in recent forms or, if present are small and embedded in the skin.  AMPHIBIANS Conraua goliath (Goliath Frog) Andrias japonicus (Giant Salamander) Paedophryne amauensis (Dwarf Frog)  EVOLUTION Adaptation to land required three major changes (evolution) in body structure: – Two pairs of limbs to replace fins of fishes – Lungs to replace gills of fishes for breathing – Land-adapted (stronger) skeleton Trends in amphibian evolution: Crossopterygians (lobe-finned fishes)- Devonian Ichthyostegids (“missing link” between fishes and amphibians)- Upper Devonian (345 million years ago) : 3 feet long, tailed, four limbs, heavy fish- like skull Labyrynthodonts (Stegocephalians)- Lower Carboniferous (300 m years ago) to Triassic (100 m yeaqrs ago): salamander-like Lepospondyli, Temnospondyli gave rise to modern Amphibia (Lissamphibia) Lissamphibia (modern amphibians)- late Carboniferous and early Triassic  SYSTEMATICS Class: AMPHIBIA Order: ANURA (SALIENTIA)-(Frogs, toads) – Tailless amphibians – Elongated hindlimbs – Larvae referred to as tadpoles – External fertilization, – About 2000 species worldwide Order: URODELA (CAUDATA)- (Salamanders, newts, sirens) – Tailed amphibians – Gills retained or lost – About 300-450 species worldwide Order: APODA (GYMNOPHIONA)- (Caecilians) Legless amphibians Elongate bodies Blind, burrowing forms About 165 species worldwide  AMPHIBIANS-ANURA Bufo regularis (Common Toad) Bufo maculatus (Toad) Hylarana [Amnirana]galamensis Phrynobatrachus accraensis  AMPHIBIANS-ANURA (2) Dendrobates azureus Silurana tropicalis (Clawed Frog) (Arrow-poison Frog) Hyperolius concolor (Reed Frog) Rhacophorus reinwardtii  AMPHIBIANS-URODELA Ambystoma maculatum (Spotted Salamander) Andrias japonicus (Japanese Giant Salamander)  AMPHIBIANS-APODA Geotrypetes seraphini (West African Caecilian)  GENERAL BIOLOGY FEEDING AND DIGESTION Carnivorous- feeding on invertebrates, fishes, small rodents, birds, etc. Long, sticky tongues fastened in front of wide gaping mouth (exc. Tongue- less frogs) Homodont and polyphyodont dentition, but some toads (e.g. Bufo, Pipa) are toothless No digestive enzymes in saliva Undifferentiated intestines in caecilians, partly differentiated in urodeles, and well-differentiated in anurans  GENERAL BIOLOGY (2) SKIN Loosely attached to body; made up of two parts: Epidermis: Several layers thick, with horny outermost layer (stratum corneum) which protects deeper skin layers Contains chromatophores (special pigment cells) for camouflage Contains skin glands which serve various functions Dermis: Relatively thin layers with two sub-layers highly vascularized (respiration): – Stratum spongiosum: Outer, loosely-organized – Stratum compactum: Inner, more compact Most adults have lungs but rely on skin for additional oxygen. Several types of salamanders have no lungs or gills and obtain oxygen through their skin.  SKIN GLANDS Mucous Glands: Moistens skin; medium of gas exchange Poison Glands: Referred to as parotids in toads; for defensive purposes; some of the toxins even deadlier than snake venom (e.g. arrow-poison frogs) Hedonic Glands: “Pleasure-giving” glands in salamanders (chin, face tail) for stimulating females Thumb Pads: Found in male anurans during breeding season (for stimulating females)  SKELETO-MUSCULAR SYSTEM Skeleton more rigid than in fishes, with well-developed endoskeleton providing the framework for muscle attachment and protection for the nervous system Teeth may be present; in the upper jaw Ribs poorly developed in modern amphibians (absent in anurans) and not in contact with the sternum as found in higher vertebrates (no thoracic basket) Two pairs of limbs with four toes on the forelimb and five on the hindlimb Limbs extend laterally from body so when animal is not moving, body rests on ground (incomplete adaptation to terrestrial existence)  EXCRETION AND OSMOREGULATION Kidneys long and narrow anteriorly in urodeles, compact and dorso- ventrally flattened in anurans, and long and uniform in caecilians Striking a balance between water intake through skin and water loss through kidneys Larvae produce copious urine (ammonia) to eliminate excess water Chief excretory product during metamorphosis is urea  RESPIRATION Most respire by means of external gills during the larval or tadpole stage Lungs are simple, sac-like structures, with smooth inner surfaces in some aquatic forms; in most anurans the walls contain many folds lined with alveoli; anuran lungs are the most complex (alveoli present) Lung ventilation mechanisms rather ineffective compared to other land vertebrates, thus cutaneous (skin), buccal (mouth), pharyngeal (throat), branchial (gill), and pulmonary (lung) respiration Most amphibians respire to some extent through the skin but some, (e.g. plethodontid salamanders) which lack both lungs and gills as adults obtain oxygen entirely through the skin and the oral epithelium)  CIRCULATION Three-chambered heart (2 auricles, 1 ventricle); valves present so only slight mixing of pulmonary and systemic circulations In most amphibians and lungfishes, the heart receives both deoxygenated blood from the body and oxygenated blood from the lungs Blood from the body enters the right atrium then the right side of the ventricle, and is pumped to the lungs Oxygenated blood from the lungs enters the left atrium through pulmonary veins into the left side of the ventricle, and pumped to the body  REPRODUCTIVE BIOLOGY VOCAL SACS & MATING CALLS First vertebrates to develop vocal apparatus Anuran males possess vocal sacs (outpouchings from mouth cavity) for amplifying sound when filled with air Females also make ‘escape’ calls to startle predators, and ‘release’ calls to alert males after eggs are laid Mating calls are species-specific (reproductive isolation) and are attractants to breeding sites  REPRODUCTIVE BIOLOGY (2) SEXUAL MATURITY & BREEDING SEASON Age of sexual maturity varies widely from 1 year to 3 years Large urodeles (e.g. Cryptobranchus) mature at 5-6 years Breeding seasons are influenced by temperature and rainfall (eggs must be laid in sufficient moisture conditions; young must hatch in conditions of abundant food Tropical amphibians undergo ‘explosive breeding’ at the beginning of the rainy season  REPRODUCTIVE BIOLOGY (3) SEX RECOGNITION Sexual differences may be permanent or temporary (i.e. appear during the breeding season- nuptial pads in male anuran forelimbs) Most salamanders utilize behaviour and odour from hedonic glands in sex recognition Male European newts are brightly-coloured, and display in front of females, which then move towards them  REPRODUCTIVE BIOLOGY (4) COURTSHIP & MATING Amphibians undergo liebespiel (‘love play’), with the male call powerful enough to stimulate female; in some species, non-calling ‘satellite’ males lurk near the callers and intercept approaching females In most anurans, males often just jump on the back of any passing female The anuran copulatory embrace (amplexus) involves the female coming under the male and nudging him to be clasped in one of two ways: – Axillary Amplexus: Clasping behind the forelimbs – Inguinal Amplexus: Clasping in front of the hindlimbs Male salamanders arrive first at the breeding grounds, followed later by females, which then lays eggs to be fertilized by males  REPRODUCTIVE BIOLOGY (5) EGG-LAYING Numerous fairly small eggs are laid, enclosed in jelly secreted from female oviduct Jelly swells enormously after absorbing water and becomes sticky (anti-predator, heat trapping mechanism) Eggs are mesolecithal (moderately-yolked) and develop into gilled aquatic larvae Clutch size generally varies inversely as size of egg and amount of yolk (e.g. Sminthillus lays a single egg; common frogs and toads lay up to 20,000 eggs) In various frogs and salamanders, egg incubation period varies from 1-4 days to 9 months  REPRODUCTIVE BIOLOGY (6) FERTILIZATION Male amphibians lack intromittent organs, but one genus Ascaphus (‘tailed’ frog) uses a ‘tail’ as intromittent organ External fertilization (pseudocopulation, amplexus) in anurans, with sperm shed over eggs as they are laid One anuran genera, Nectophrynoides, undergoes internal fertilization Oviparity (egg-laying) is the rule, but some salamanders have internal fertilization In salamanders, male deposits several packets of spermatophores, which the female picks up with her cloacal lips Most caecilians have internal fertilization and are ovoviviparous, with males possessing some form of copulatory organ (cloacal extension)  REPRODUCTIVE BIOLOGY (7) NEOTENY (PAEDOMORPHOSIS) Retention of larval structures (e.g. gills) into adulthood, as found in urodeles. Two types: – Genetically-Fixed (Obligate ): Animal’s tissues fail to respond to secretions of metamorphosis-initiating secretions from thyroid gland (e.g. Siren, cave-dwelling plethodontids). No metamorphosis ever occurs – Environmentally-Induced (Facultative): Metamorphosis triggered only when environmental conditions become unfavourable (e.g. pond drying up)- e.g. Ambystoma. Favourable conditions will trigger metamorphosis – Adaptive Significance: More exploitation of aquatic environment provided favourable conditions continue to exist Adaptation to harsh terrestrial conditions  GROWTH & LONGEVITY Growth period after metamorphosis and before sexual maturity varies from 1-3 or several years Much slower growth rate after sexual maturity Longevity – Xenopus laevis (Clawed Toad)…………………….15 years – Rana catesbeiana (Bullfrog) ………………………..16 – Salamanders (most) …………………………………25 – Siren lacertina (Siren) ……………………………….25 – Amphiuma means (Congo Eel) ……………………..27 – Bufo bufo (Toad) ……………………………………36  BENEFITS OF AMPHIBIANS Insect population control Source of food (whole or part) Biological/medical specimens for dissections (introduction to human anatomy) Medicinal use of some secretions (Chinese medicine) Human pregnancy tests Aesthetics (use in art motifs) Religious symbols in some primitive societies  Prof. Daniel ATTUQUAYEFIO Department of Animal Biology & Conservation Science (DABCS) University of Ghana, Legon  INTRODUCTION  Latin: “repto” = crawl/creep  First true land vertebrates (tetrapods)  Worldwide species: 7,000, comprising 6,000 (86 %) lizards and snakes  Other reptile groups: chelonians, crocodiles, tuataras, amphisbaenids  INTRODUCTION (2)  Largest reptile: Crocodylus porosus (crocodile) (SE Asia)- 10 m long  Smallest reptile: Evoluticauda tuberculata (Dwarf chameleon) (Madagascar) – 1.8 cm long  Largest lizard: Varanus komodoensis (Komodo dragon) (Indonesia) – 4 m long  Largest snake: Eunectes murinus (Anaconda) (S. America) – 11 m long  INTRODUCTION (3)  Longest snake: Python reticulatus (Reticulated python) (Asia)- 11.5 m  Largest snake (Africa): Python sebae (African/rock python)- 10 m  Largest snake (Venomous): Ophiophagus hannah (King Cobra)- 5.5m  Most venomous snakes: Enhydrina schistosa (Beaked sea snake), Oxyuranus scutellatus (Taipan), Bungarus candidus (Banded krait), Acanthophis antarcticus (Death adder), Dendroaspis polylepis (Black mamba)  GENERAL FEATURES  Internal fertilization with intromittent organ (hemipenis)  Direct development (eggs develop into adults with no aquatic larval stage) so no need for water for reproduction.  Dry scaly skin to prevent desiccation due to temperature fluctuations and abrasion during movement.  Large heavily-yolked, shelled and cleidoic eggs (covered with embryonic membranes: amnion, chorion and water) and contains everything the embryo needs.  Generally oviparous, but some evolve ovoviviparity  Ectothermic – undergo behavioural thermoregulation  GENERAL FEATURES (2)  Very effective excretory system – more complex/efficient kidney ensures a lot of water is retained in the body. Uric acid can be excreted with little water in the form of crystals/paste  Well-ossified skeleton for efficient movement on land  Efficient pulmonary respiration – respiration through lungs (exc. Chelonia)  Highly-developed cerebral cortex makes them capable of more complex behaviour than amphibians  Three-chambered heart (two auricles and one ventricle) but with an incomplete septum dividing the ventricle (exc. Crocodylia)  EVOLUTION  Labyrinthodonts (Amphibia): - 350 million years ago  Seymouriamorps (Stem Reptiles): - ‘missing links’ (amphibian/reptile)  Cotylosaurs (Primitive Reptiles): - 300 million years ago  Anapsida- Chelonians (Tortoises/turtles/terrapins)  Lepidosauria (Diapsida)- (Squamata – Lizards/Snakes)  Archosauria (Thecodonts) (Dinosaurs, Crocodilia, Aves)  Theromorpha (Mammal-Like Reptiles)- Mammalia  SYSTEMATICS Class: REPTILIA Subclass: ANAPSIDA Order: CHELONIA (Shelled reptiles) Family: TESTUDINIDAE (Land chelonians-tortoises)-Kinixys Family: DERMOCHELIDAE (Leatherback turtles)- Dermochelys Family: PELOMEDUSIDAE (Terrapins)- Pelomedusa Family: CHELONIDAE (Marine turtles)- Chelonia Subclass LEPIDOSAURIA Order: RHYNCHOCEPHALIA (Tuataras) Family: SPHENODONTIDAE (Tuataras)- Sphenodon  SYSTEMATICS  Class: REPTILIA  Subclass: LEPIDOSAURIA Order: SQUAMATA (Lizards, snakes, amphisbaenians) Suborder: LACERTILIA (SAURIA) (Lizards) Family: AGAMIDAE (Agama/rainbow lizatds)- Agama Family: SCINCIDAE (Skinks/snake-lizards)- Trachylepis (Mabuya) Family: CHAMAELEONIDAE (Chameleons)- Chamaeleo Family: VARANIDAE (Monitor lizards)- Varanus Family: GEKKONIDAE (Geckos)- Hemidactylus Family: GERRHOSAURIDAE (Plated lizards)- Gerrhosaurus Family: HELODERMATIDAE (Gila monsters)- Heloderma Family: ANGUIDAE (Legless lizards, slow worms)- Anguis  SYSTEMATICS  Class: REPTILIA  Subclass: LEPIDOSAURIA Order: SQUAMATA Suborder: SERPENTES (OPHIDIA) (Snakes) Family: LEPTOTYPHLOPIDAE (Worm/thread snakes)- Leptotyphlops Family: TYPHLOPIDAE (Blind/glass snakes)- Typhlops Family: BOIDAE (Pythons and boas)- Python, Eunectes Family: COLUBRIDAE (Typical snakes)- Philothamnus, Psammophis Family: ELAPIDAE (Cobras, mambas)- Naja, Dendroaspis Family: VIVERIDAE (Vipers, adders)- Bitis, Causus Suborder: AMPHISBAENA (ANNULATA) (Worm lizards) Family: AMPHISBAENIDAE (Worm lizards)- Amphisbaena  SYSTEMATICS  Class: REPTILIA  Subclass: ARCHOSAURIA Order: CROCODILIA Family: CROCODILIDAE (Crocodiles)- Crocodilus Family: ALLIGATORIDAE (Alligators)- Alligator Family: GAVIALIDAE (Gavials)- Gavialis  SYSTEMATICS Class: REPTILIA Subclass: ANAPSIDA Order: CHELONIA (TESTUDINES)  Shelled reptiles  Toothless  327 species worldwide. e.g. - Dermochelys coriacea (Leatherback turtle) Pelomedusa subrufa (MarshTerrapin) Kinixys sp. (Hinged Tortoise)  CHELONIA Pelomedusa subrufa (Marsh Terrapin) Dermochelys coriacea (Leatherback Turtle) Kinixys sp. (Hinged Tortoise) Pelusios gabonensis  SYSTEMATICS (2)  Subclass: LEPIDOSAURIA (Scaly Reptiles)  Order: SQUAMATA (Lizards/Snakes) Suborder: LACERTILIA/SAURIA (Lizards) ○ Agamas, skinks, wall geckos, chameleons, monitor lizards ○ 30 families worldwide ○ 5,634 species ○ E.g. Hemidactylus brookii (Wall gecko) Trachylepis perrotettii (Orange-flanked skink) Agama agama (Rainbow lizard) Varanus niloticus (Nile monitor lizard)  LACERTILIA Agama agama (Rainbow Lizard) Varanus niloticus (Nile Monitor) Chamaeleo senegalensis (Chameleon) Hemidactylus brookii (Wall Gecko)  LACERTILIA (2) Trachylepis [Mabuya] perottetii (Orange-flanked Skink) Mabuya quiquetaeniata (Five-lined Skink)  SYSTEMATICS (3) Subclass: LEPIDOSAURIA Order: SQUAMATA Suborder: SERPENTES (OPHIDIA) (Snakes)  Limbless, no eyelids; no eardrum  10 families; 3,000 species e.g. Python regius (Royal python) Philothamnus sp. (Green tree snake) Naja nigricollis (Spitting cobra) Dendroaspis viridis (Green mamba) Bitis arietans (Puff adder)  SERPENTES Bitis gabonica Python regius (Gaboon Viper) (Royal Python) Python sebae (African Python) Bitis arietans Typhlops sp. (Puff Adder) (Blind/Glass Snake)  SERPENTES (2) Dendroaspis viridis (Green Mamba) Thelothornis kirtlandii (Twig Snake) Philothamnus sp. Naja nigricollis (Spitting Cobra) Dispholidus typus (Green Tree Snake) (Boomslang)  SYSTEMATICS (3) Subclass: LEPIDOSAURIA Order: SQUAMATA Suborder: AMPHISBAENA (ANNULATA) (Worm Lizards)  Blind, subterranean  Insectivorous, limbless-  1 family; 130 species  E.g. Amphisbaena kraussi (Worm Lizard) Order: RHYNCHOCEPHALA (Tuataras)  ‘Living fossils’  One existing species- discovered in 1831 off New Zealand E.g. Sphenodon punctatus (Tuatara) AMPHISBAENA and TUATARA Amphisbaena sp. Sphenodon punctatus (Worm Lizard) (Tuatara)  SYSTEMATICS (4) Subclass: ARCHOSAURIA  Order: CROCODILIA  Largest living reptiles (crocodiles, alligators, gavials)  Amphibious  Predatory, 23 species  E.g. Crocodylus niloticus (Nile crocodile) Alligator mississippiensis (Alligator)  CROCODILIA Crocodylus niloticus (Nile Crocodile) Osteolaemus tetraspis (Dwarf Crocodile)  GENERAL BIOLOGY Feeding and Digestion  Majority are carnivorous  Tongue  Protrusible (Squamata); longest in chameleons, forked (bifid) in snakes/monitors  Non-protrusible (Crocodilia, Chelonia)  Well-developed homodont dentition (Chelonia are toothless)  Acrodont (non-socketted, top of jaw)- Squamata  Pleurodont (non-sockcetted, side of jaw)- Squamata  Thecodont (socketted)- Crocodilia  Large jaw muscles for crushing prey  Diet related to size/age; juveniles feed on smaller prey (insects, small invertebrates, etc.) while adults feed on larger prey (rodents, large vertebrates, etc.) Feeding and Digestion (2)  Feeding and Digestion (3)- Snakes  Teeth recurved (curved backwards)- Modified for swallowing, not chewing  Some teeth modified into fangs for venom injection  Back/rear) fangs (Colubridae); front fangs (Elapidae, Viperidae)  Venom (modified saliva)  Neurotoxic (Nerve – acting)- Cobras/mambas  Haemotoxic (Blood-acting)- Vipers  Venom gland (modified salivary gland)  Quadrate bones (paired)- serve as hinges (swallowing large prey)  Loosely-connected upper and lower jaws (open > 90o)  Shingle-like scale arrangement  GENERAL BIOLOGY (2) Osmoregulation, Gas Exchange  Osmoregulation  Bladder is absent in crocodiles, and bi-lobed in lizards/chelonians  Excretory Product is uric acid, which is non-toxic with low solubility  Urine concentrated and pasty for water retention  Gas Exchange  More efficient than in amphibians, entirely dependent on lungs (no aquatic larval stage)  Chelonians undergo cloacal and pharyngeal respiration (ribs inefficient because of attachment to shell)  GENERAL BIOLOGY (3) Integument (Skin)  Skin dry and scaly (keratinized) to enables occupation of dry habitats, and also crawling over rocks and abrasive sand without injury  Chelonians- skin modified into a shell comprising of a carapace (dorsal) and plastron (ventral)  Thin epidermis shed periodically  Dermis supplied with chromatophores (colour-bearing shells)  Periodic ecdysis (shedding) in squamates (snakes- whole, lizards- in bits)  GENERAL BIOLOGY (4) Circulation  Circulation  Heart more efficient than in amphibians  Three-chambered in squamates and chelonians  Four-chambered in crocodiles  GENERAL BIOLOGY (5) Skeleto-muscular System  Skull is light and kinetic (loosely-attached bones) in snakes; robust and solid in crocodiles  Ribs  Well-developed for protection of heart, lungs  Vertebral Column  Less regionalized than in mammals (four sections- cervical, trunk, sacral, and caudal)  Snakes have 130-500 vertebrae, each with ribs  Tail autotomy (self-cutting) in lizards  Chelonians – Trunk vertebrae fused to dermal bones of carapace  Limbs  Pentadactyly (five digits)  Some primitive snakes (pythons) possess spurs (vestigial limbs)  GENERAL BIOLOGY (6) Nervous and Sensory Systems  Brain  Similar to that of amphibians, but larger cerebrum (forebrain) and more complex behaviour  Vision  Reptiles have well-developed colour vision; tree snakes have good binocular vision  Brille (transparent window) replaces eyelids in snakes  Hearing  Tympanic membrane present in chelonians and lizards but absent in snakes  Snakes lack middle and outer ear and tympanum; perceive vibrations from substrate through lower jaw and quadrate bones/inner ear  Crocodiles have the best developed inner ear  Nervous and Sensory Systems (2)  Chemoreception (Jacobson’s Organ/Vomeronasal Organ)  Organ of smell in reptiles which is part of the nasal sac which communicates with the mouth  Best-developed in the squamates, opening directly into the roof of the mouth  Forked tongue of snakes picks chemical particles from air inserts it into Jacobson’s organ for analysis (recognition of prey, enemies, mates)  Heat Reception (Thermovision)  Pit-organs possessed by some snakes (e.g. rattlesnakes, pythons) on the head serve as heat sensors  The heat sensitive pits are important for hunting warm-blooded prey (birds, mammals) at night (detects 0.002 - 0.003 oC difference)  GENERAL BIOLOGY (7) Locomotion  Reptiles are crawling animals which can also swim  The most highly-adapted reptile locomotion is found in snakes, with 4 types:  Serpentine (Lateral Undulation): Typical snake S-shaped movement- ‘swimming on land’ or ‘slithering’. Used in fast movement (chasing or escape)  Rectilinear (Caterpillar): Movement in straight line; very slow. Mostly used by heavy-bodied snakes and for stalking prey  Concertina: Movement forward or backward in small space (e.g. burrowing, tree climbing)  Sidewinding: Specialized serpentine locomotion with body lifted off ground (‘looping’). Enables movement with speed across loose (sandy) and hot (desert) surfaces with minimum surface contact (body at 60o in direction of travel)  GENERAL BIOLOGY (8) Thermoregulation  Reptiles are ectothermic (behavioural thermoregulation), with optimal temperatures for survival (preferred or eccritic temperature or thermal preferenda  Lizards tend to have higher thermal preferenda than snakes  Snakes (26 oC)  Lizards (33 oC)  Alligator (34 oC)  Turtle (28 oC)  Thermoregulation (2)  Behavioural Thermoregulation  Shuttling (Basking and sheltering)  Burrowing  Hibernation/Aggregation and Coiling  Aestivation  Colour Change  Panting  Temperature and Reptile Distribution  Reptiles more resistant to cold extremes than heat extremes  Northern limits of snake distribution: 67 oN (Europe), 60 oN (Asia), 52 oN (North America)  Southern limit: 44 oS  REPRODUCTIVE BIOLOGY OF REPTILES  Three major evolutionary changes ensured complete freedom from the need to return to water to breed:  Direct development (no aquatic larval stage, and therefore no need for water to breed)  Cleidoic (self-contained) eggs with calcareous shells  Internal fertilization with an intromittent organ (hemipenis, penis)  REPRODUCTIVE BIOLOGY (2) Sexual Dimorphism  Sexually-mature reptiles differ in shape, size, coloration, etc. (sexual dimorphism), and this may be temporary (seasonal) or permanent  Lizards: Males bigger, with brightly coloured heads, enlarged crests, horns and throat fans (dewlaps)  Snakes: No colour variation; males have longer tails with thicker bases, but body proportionately shorter (hemipenes)  Chelonians: Males and females equal size; no colour variation  REPRODUCTIVE BIOLOGY (3) Sex Recognition and Courtship  Females- passive sex; most males don’t recognize females  Some reptiles use behaviour, appearance, scent and touch to recognize females  Some male lizards use head-bobbing, dewlaps, etc. to attract females  Some snakes undergo ‘combat dances’ to compete for females (e.g. vipers); monitors ‘wrestle’ for females  Reptiles undergo ‘liebespiel’ (love play) during courtship (grabbing, nudging, tonguing, chinning, postures and displays)  REPRODUCTIVE BIOLOGY (4) Copulation and Fertilization  All reptiles undergo internal fertilization  Lizards possess well-defined male territories overlapping with several female territories  Snakes undergo congregation mating’ in hibernacula with the use of scent trails  Hemipenis next to female is everted and thrust into cloaca of the female where it is held in place by spines (calyces)  REPRODUCTIVE BIOLOGY (5) Egg-Laying and Hatching  Fertilized ovum encased in shell secreted by oviducal walls and laid in oviparous species  Most reptiles lack parental care, which is however present in some species like skinks and crocodiles)  Some reptiles are ovoviviparous (give birth to live young)- boas, vipers, sea snakes)  Squamates: At hatching, an egg-tooth on the snout breaks open the egg  Chelonians/Crocodiles: A horny projection (caruncle) on the snout pierces the egg at hatching  Snakes: Fangs well-developed at hatching in venomous snakes; hoods are present in cobras  REPRODUCTIVE BIOLOGY (6) Growth and Longevity Species Max. Life-Span (Yrs.) Heloderma suspectum (Gila Monster) 20 Crotalus sp. (Rattlesnake) 22 Eunectes murinus (Anaconda) 29 Naja melanoleuca (Black Cobra) 29 Anguis fragilis (Slow Worm) 54 Alligator sp. (Alligator) 56 Sphenodon punctatus (Tuatara) 77 Geochelone gigantea (Giant Tortoise) 152  DIVERSITY  Class REPTILIA Subclass ANAPSIDA Order: Chelonia Subclass LEPIDOSAURIA Order: Rhynchocephalia Order: Squamata Suborder Lacertilia (Sauria) Suborder Serpentes (Ophidia) Suborder Amphisbaenia Subclass ARCHOSAURIA Order: CROCODYLIA  DIVERSITY (2) Order: CHELONIA (TESTUDINES) Families: DERMOCHELYDAE (Leatherback turtles)- Dermochelys CHELONIIDAE (Marine Turtles)- Chelonia mydas TRIONYCHIDAE (River Turtles)- Trionyx triunguis TESTUDINIDAE (Land Tortoises)- Kinixys sp.. PELOMEDUSIDAE (Terrapins)- Pelomedusa subrufa  DIVERSITY (3) Order: SQUAMATA (Lizards/Snakes) Suborder: LACERTILIA/SAURIA (Lizards) Families: GEKKONIDAE (Geckos)-Hemidactylus brookii SCINCIDAE (Skinks/Snake-Lizards)- Trachylepis perrotettii) AGAMIDAE (Rainbow Lizards)- Agama agama, Draco volans VARANIDAE (Monitor Lizards, Komodo Dragons) Varanus niloticus, CHAMAELEONIDAE (Chameleons)- Chamaeleo gracilis GERRHOSAURIDAE (Plated Lizards)- Gerrhosaurus major ANGUIDAE (Slow Worms)- (Anguis fragilis) HELODERMATIDAE (Gila Monster, Beaded Lizard)  DIVERSITY (4) Order: SQUAMATA Suborder: SERPENTES (OPHIDIA) (Snakes)  Families: LEPTOTYPHLOPIDAE (Worm Snakes)- Leptotyphlops sp. TYPHLOPIDAE (Blind/Glass Snakes)- Typhlops sp. PYTHONIDAE (Pythons)- Python regius, P. sebae BOIDAE (Boas)- Eryx COLUBRIDAE (Common/Typical Snakes)- (Philothamnus sp.) ELAPIDAE (Cobras/Mambas)- Naja nigricollis, Dendroaspis viridis VIPERIDAE (Vipers)- Bitis arietans, B. gabonica,  DIVERSITY (5)  Order: SQUAMATA ○ Suborder: AMPHISBAENA (Worm Lizards)- ○ Family: AMPHISBAENIDAE (Amphisbaena kraussi)  Order: RHYNCHOCEPHALiA (Tuataras) - Sphenodon punctatus Subclass: ARCHOSAURIA  Order: CROCODILIA Families: CROCODILIDAE (Crocodiles)- (Crocodylus niloticus) ALLIGATORIDAE (Alligators)- Alligator mississippiensis GAVIALIDAE (Gavials/Gavials) ABCS 341 - Comparative Chordate Biology Module 5: AVES - BIRDS Origin & Evolution Taxonomy & Morphology Behaviour & Adaptations Ecology & Conservation May 2021 Prof. L. H. Holbech, Wi-fi Network: DABCSLHH ; Drive: LHServer; User name: LHUser ; Password: ANKASA2017 1 ABCS 341: Objectives of Lecture 1 - Birds: Origin, Evolution & Taxonomy 1. An Introduction to the major theories of avian origin and flight Reptilian Ancestor - Feathered Dinosaurs - Early Birds Evolution of Feathers and Flight 2. An Overview of 4 major taxonomical avian divisions and sub-divisions: Ratites - Carinates - Non-Passeriform - Passeriformes 3. A Comparison of Non-passeriform and Passeriform Birds: Size - Species Diversity - Morphology - Ecology - Biology 4. An Account of the varieties and diversity of 12 selected orders: Large Ancient Birds: Flightless Birds & Marine Birds Important to Humans: Fowl-like Birds - Waterfowl - Raptors Primitive Perching Birds: Columbids - Parrots - Turacos - Cuckoos 2 ABCS 341: The Origin & Evolution of Birds: Archaeopteryx - The Earliest Bird? Meaning = ‘Ancient Wing’ (Hermann von Meyer) Reconstruction Limestone quarries in southern Germany A. lithographica (1861): 11 whole fossils A. bavarica (1992): 1 feather fossil Size: Pigeon-Crow size (35-50 cm) 148-152 mya Aerial? Arboreal? Cursorial? 3 ABCS 341: Archaeopteryx - Primitive reptilian and advanced bird features Advanced features: Adult Pigeon - Highly asymmetrical feathers for flight Hoatzin - Long forearms for flight - Anisodactyl foot with hallux for perching - Fused tibio-tarsus and digitigrade Primitive features: - Heavy toothed jaws - Unfused hand bones (no carpometacarpus) Archaeopteryx head reconstruction - Unfused tail bones (no pygostyle) - Pelvic girdle unfused with sacral vertebrae (no synsacrum) Archaeopteryx Young - No uncinate processes - No deep keels (carina) on sternum Hoatzin From Feduccia (1999) - Dorsal elevators (no supracoracoideus) Hoatzin Wing claws 4 ABCS 341 - The Origin & Evolution of Birds & Flight - 4 Competing Theories Bipedal-Cursorial or Quadropedal-Arboreal? (a) ’Cursorial Archaeopteryx Ground-up’ THE(C?R?)O(D?P?)O(NT?D?) Archaeopteryx Compsognathus (b) ’Wing-assisted Running - Stalking’ F roG m il(207) THEROPOD Fossil Terrestrial Theropod or Longisquama: (c) ’Wing-assisted Incline Arboreal Thecodont? Elongated Scales or Running - Climbing’ Proto-feathers? THECODONT (d) ’Arboreal Tree-down’ 200 mya Longisquama insignis Fossil 5 ABCS 341: The Origin & Evolution of Birds and Flight – Chinese Early Birds 120 mya: Microraptor gui (2003) 160 mya: Anchiornis huxleyi (2009) Bi-plane gliders Arboreal Bi-tailed gliders Feathered legs Terrestrial Cursorial 156-161 mya: Xiaotingia zhengi (2011) 120-122 mya: Jeholornis prima (2002) 6 ABCS 341: The Origin & Evolution of Birds & Flight - Tentative Cladogram Most Theropod dinosaurs were feathered Compsognathus → Archaeopteryx → Fowl 9 Dinosaurian fossil feather types 4 in extant birds 7 ABCS 341: Bird Taxonomy - The Ratites or Flightless Birds Ratites (c. 60 species) Ostrich No keeled sternum (carina) All flightless – medium-large size Poorly developed wings Wings-feathers used in displays only Good running ability (cursorial) Plumulaceous feathers for insulation Ostrich Feather Cassowary Ostrich - Africa: only 2 toes, huge size Tinamou Rhea, Tinamous - South America Cassowary, Emu - Australia: large Kiwi - New Zealand: mammal-like Moa, Elephant birds – Extinct birds Kiwi Rhea Emu 8 ABCS 341: Bird Taxonomy - Carinate Birds - Non-passerines & Passeriformes Non-passerines - 29 orders incl. ratites (5) Passeriformes = 1 order Generally large in size Generally small-sized sparrow-like birds Exceptions: Hummingbirds, swifts Exceptions: Crows, raven, magpies Mostly primitive perching birds Mostly small perching ‘sparrow birds’ Exceptions: parrots, pigeons, wood peckers Flying birds, many long-distance migrants Both terrestrial, aquatic and marine Mostly terrestrial and insectivorous birds Not all are flying, although with carina Many intelligent with advanced behaviour Flightless: Penguins, Auks, some rails Also referred to as ‘songbirds’ Some are extremely good flyers: raptors Males sing to attract females/repel rivals pigeons, doves, rollers, waders, ducks, Some may have up to > 2,000 song types Mostly poor song ability, but many colourful The song producing organ = syrinx more Visual courtship behaviour (e.g. in leks) advanced than non-passerines Often simple nests (e.g. tree hole, ground) Also advanced nest building, e.g. weavers Relatively fewer species, due to larger size >60% (c. 6,410) of all bird species (c. 10,710) 9 ABCS 341: Bird Taxonomy – ORDER Galliformes - Fowl-like Birds Eurasian black grouse Tetrao tetrix Fowl, guineafowl, grouse, peacock, partridge: Medium-large size (0.5 up to +10 kg) Ground-dwelling omnivorous and gregarious Short and stout rounded powerful wings Large keel (carina) for strong pectorals Heavy chest: Strong ‘explosive’ flyers Stone partridge Ptilopachus petrosus Strong legs (good runners - cursorials) Helmeted guineafowl Sexually dimorph - polygamy common (leks) Numida meleagris Many domesticated and game birds High economical value to humans (meat, eggs) Chicks largely precocial and fast developing Crested guineafowl Red jungle fowl Gallus gallus Indian blue peacock Pavo cristatus Wild turkey Meleagris gallopavo Guttera edouardi 10 ABCS 341: Taxonomy - ORDER Falconiformes - Diurnal Birds of Prey = ‘Raptors’ Extremely acute vision (tubular eyeball) Strong claws (talons) for grabbing Sharp, curved beak for tearing, ripping Strong flyers, many long-distance migrants Vultures locate carcasses by vision/scent Eagles, huge, powerful, but lightweight Some falcons sense ultraviolet light rays Crowned Eagle with monkey Harpy Eagle with rabbit Falconers use raptors for hunting/scaring Martial Eagle with antelope Most raptors are wholly protected species Many raptors persecuted by humans Stellers Many raptors wary of humans Sea Eagle Black Kite Falcons have notch on beak Falcon beak Rüppel’s Griffon = 11,200 m Eagle talons Lappet-faced Vulture Goshawk Falconry with hawk 11 ABCS 341: ORDER Anseriformes - Waterfowl - Adaptations to Aquatic Life Ducks - Geese - Swans Knob-billed Swan Cygnus olor Good swimmers and divers Webbed feet (palmate) Heavy birds (> 3 - 10 kg) Grey Goose Anser anser Powerful flyers and migrants Important Economic Birds: Roasted Duck Down feathers (pillows/duvets) and meat Swans aquatic herbivores (long neck used) Geese terrestrial herbivores (stout beaks) Mallard Duck Anas platyrhynchos Ducks filter feed on algae and zooplankton Shoveling Duck Ducks filter particle food from ingested Use of Down Feathers water by using tongue (in upper jaw) as a pumping piston and lamellae strains Suspension Filter-feeding Beak food as the head/beak is moving side wards. 12 ABCS 341: Taxonomy - Marine Birds - Pursuit Divers, Plunge Divers & Surface Gleaners Pursuit Divers Plunge Divers Surface Gleaners Penguins: Sphenisciformes Pelicans: Pelicaniformes Albatrosses: Procellariformes Wings = flippers Lower jaw widening Long distance high-speed gliding Feathers tip-overlying Large gular pouch Large pre-orbital salt glands Feathers downy aftershaft Airsac chest cushion Longest wingspan (Wandering) Thick subcutaneous fat layer Heavy with large wingspan Skimmers: Charadriiformes Wing-propelled diver (> 530m) Among largest carinate birds Surface prey skimming Underwater ’flying’ (4-5, 16min) Emperor Large sternum and keel (carina) Penguin Terns – (Charadriiformes): Lower mandible > upper Strong flyers African Reduced bone pneumatisation & air sacs Skimmer Auks: Charadriiformes Small size Northern hemisphere diving ’penguins’. Very agile Cormorants: Pelecaniformes Many migrants High feather wettability (reduce buoyancy) Hunted in Foot-propelled Ghana by Totipalmate feet fishermen Tern Wandering Great Auk † Cormorant Pelican Albatross 13 ABCS 341: Non-passeriform Primitive Perching Birds - Some Examples Pigeons and Doves Parrots and Turacoes Cuckoos (Cuculiformes) (Columbiformes) (Psittaciformes & Musophagiformes) Brood parasites (egg mimicry) Strong long-distance flyers Arboreal fruit and seed eaters Parasitizes specific groups Good homing ability (migratory) Global pet trade (parrots) Breeding host dependent Domestic use (air services, meat) Hunted in Ghana (turacos) Shy, elusive and secretive Arboreal or terrestrial Intelligent/long-lived (parrots) Insectivorous, mostly arboreal Fruits, insects, seeds (omnivore) Social complexity and gregarious Specific songs easy to identify Cuckoo chick pushing host eggs Rose-ringed out of the nest Parakeet From Billions to None in 100 years! Peace Dove Hunted to Extinction! Great Blue Turaco Host egg mimicry of cuckoo By Man! Host feeding the cuckoo chick 14 ABCS 341: Summary of Lecture 1 - Birds: Origin, Evolution, Taxonomy 1. Two Major Competing Theories for Reptilian Ancestral Origin of Birds: Theropod - Feathered Dinosaurs - Cursorial - Bipedal Thecodont - Elongate Scaly Lizards - Arboreal - Quadropedal 2. Three Major Theories for the Evolution of Avian Flight: Cursorial Ground-Up (Theropod Bipedals) Arboreal Tree-Down (Thecodont Quadropedals) Semi-Arboreal Trunk Climbing (Theropod Bipedals) 3. Two Major Taxonomical Avian Divisions: Ratites = Flightless Birds & Carinates = Flying Birds (10,711 sp.) 4. Two Major Taxonomical Avian Sub-Divisions: Non-passeriform Birds & Passeriformes (c. 6,410 sp. = 60%) 15 ABCS 341: Objectives of Lecture 2 - Birds: Biology, Ecology, Conservation 1. An Introduction to the General Morphological Adaptations for Flight Lightweight & Strength: Bones, Muscles, Beaks, Feet, Feathers 2. An Overview of major functional Feather types: Flight, Insulation, Protection, Sensory, Colouring, Shape 3. A Comparison of major Feet and Beak type adaptations of birds: Movement: Toe Composition, Webbing, Claws, Talons Foraging: Size, Shape, Filtering, Darting, Cracking, Probing 4. An Account of the Varieties and Diversity of: Flight Mechanism & Aerodynamics: Aspect ratio & Wing Loading Reproduction: Mono/Polygamy, Polygyny, Polyandry, Oviparity 5. An Assessment of Bird Conservation Aspects: Ecosystem Functions and Services: Human Benefits of Birds 16 ABCS 341: Bird Topography - Naming of Basic Body Parts & Feathers Body Tail Red-rumped Tinkerbird Yellow-crowned Gonolek Head Wings 17 ABCS 341: Basic Bird Morphology - Structural Lightweight Flight Adaptations Basic structures of birds Simple (Aves bird ): Morphological lightweight adaptations to flight tongue Beak: Light keratinised sheath replaces heavy jaw-bones, that are From Storer et al. (1979) thin and edentulous = toothless Tongue: Very light, non-muscular (cartilaginous), no taste buds Skin: Thin non-glandular (only uropygial preen-gland at the rump) Feathers: Light insulating and aerofoil-making integument replaces large patagium (skin-fold) as in pterosaurs and bats Bones: Many fused and hollow (pneumatic) bones, that lack marrow but reinforced by diagonal struts Lungs: Rather small, but aided by ventilation system of effective air sacs N-excretion: By virtue of uric acid concentrated Woodpecker tongue in cloaca - no urine bladder with urea and reduced metanephric kidneys Ovary: Only one ovary functionable in females Humerus usually the left bone Tendon mechanism Oviparous: Foetuses develop outside the body as of a perching bird Basic wing Anatomy eggs are incubated in nests Wing Gizzard: All birds (grinding stomach as living birds have no teeth) Crop: Mainly granivorous birds, flamingos and penguins (raptors temporary crop) From Maclean (1990) Avian & human From Proctor & Lynchfemur (1993) bone 18  The ABCS bird 341: Theskeleton: Lightweight Bird Skeleton and - Lightweight strength & Strength Maximized Herring gull humerus - Reduced bone marrow - Pneumatic with air sacs - Thin-walled but highly ossified - Reinforcement with diagonal struts - Several fused or reduced bones: - Skull - Tibiotarsus (leg) - Tarsometatarsus (foot) - Carpometacarpus (hand) - Pygostyle (reduced tail) - Clavicles fused to furcula From Proctor & Lynch (1993) - 5 digits on hand reduced to 3 - 5 digits on foot reduced to 2, 3 or 4 - Sacral region of vertebrae = synsacrum Tawny owl braincase wall Long-eared owl braincase wall From Feduccia (1999) From Feduccia (1999) 19 ABCS 341: The Bird Beak – Diversity of Foraging Adaptations Length - Width - Shape - Curvature - Hardness - Sharpness Beak characters directly related to foraging mode & ecology Short, pointed, sharp: Broad, flat, lamellirostral: Long, pointed, sharp: Insect/caterpillar picking Filtration of plankton Darting for fish Strong, pointed: Wood chiseling Shoveling & Broad, hooked, pointed: Short, powerful: Strong, pointed, curved Skimming Flesh tearing, grasping Catching aerial insects Seed cracking beak Flamingo (tongue in lower jaw): Waterflow along beak and engulfed water squeezed out when closing the beak, similar to a baleen whale - lamellae strains particles in water - algae or zoo-plankton. Duck (tongue in upper jaw): Double-piston tongue pumps water from anterior to posterior end of beak Tubeformed, hooked: Strong, powerful, hooked: and filters out particles by straining lamellae. Pelagic/aerial skimming Pine/spruce needle cutting Long, pointed: Probing in mud Long, curved, hollow Nectar licking Sharp, crossed Piston-pump Long, upward-curved: Horizontal skimming surface Cone seed picking sucking beak From Linzey (2001) 20 ABCS 341: The Bird Foot - Adaptations for Foraging and Locomotion Walking, running, perching, climbing, hanging, swimming, diving, digging, grasping & killing Foot Topography – Toe Arrangement Foot Topography - Webbing & Reinforcement From Proctor & Lynch (1993)