Ichthyology: An Introduction PDF

ICHTHYOLOGY: An Introduction  What is Ichthyology?  Study of fishes  Scientific study started in Europe  HISTORY OF ICHTHYOLOGY Carl Linnaeus – designed Binomial nomenclature (classification – Genus & species) Peter Artedi – father of Ichthyology, helped Linnaeus Approx...

ICHTHYOLOGY: An Introduction  What is Ichthyology?  Study of fishes  Scientific study started in Europe  HISTORY OF ICHTHYOLOGY Carl Linnaeus – designed Binomial nomenclature (classification – Genus & species) Peter Artedi – father of Ichthyology, helped Linnaeus Approximately 30,000 known species are classified and about 100- 200 new discoveries each year. Fish Fact Sheet NUMBER OF FISH TAXA Species,  Cold-blooded animals 12.80%  Numerous vertebrates Genera, Orders Orders, 23.47% Families 71.66% Genera Families, Species 43.30% Philippines World Orders ˜43 ˜60 Families ˜210 ˜485 Genera ˜1000 ˜4260 Species ˜3,280 ˜32,200  Fish Fact Sheet Ichthyofauna of the Philippines Total species +3,280 Freshwater 347 Seawater 3,029 Introduced 44 Endemic 120 Threatened 97 Dangerous 348 Reef associated 1,772 Pelagic 19 Deep water 350 Game fish 276 Commercial 3,280 Fishbase 2012  Fish Fact Sheet Priapiumfishes Catfishes Gobies Eels Pipefishes Needlefishes Sleepers Cyprinids Perciforms and others 211 lakes 18 major rivers 22 marshlands Characteristics of Fish Aquatic Vertebrate With gills for breathing Have scales and fins Cold blooded Mostly lay eggs  Fish v.s. Fishes Fish Fishes “There are twelve fish in this aquarium, representing five fishes”  Fish Fact Sheet Aquatic Biodiversity in the Southeast Asia: Fishes >5000 species Amphibians >300 species Aquatic reptiles >350 species Decapod crustaceans >300 species Aquatic insect >250 species Zooplankton >1000 species Benthos >1500 species Water plants >400 species Fish Fact Sheet Photocorynus spiniceps – 6.2 mm male; 46 mm female by Ted Pietsch Schindleria brevipinguish – 6.5-7.0 mm male; 7.0-8.0 mm female Paedocypris progenetica – 7.9 mm female by Maurice Kottelat and Tan Heok Hui (P. micromegethes) Pandaca pygmea – 15 mm Mistichthys luzonensis – 25 mm Rhincodon typus – 18-21 m; 25 MT COELACANTH  CLASSIFYING FISHES SYSTEMATICS – Study of Kingdom: Animalia fish diversity and evolutionary relationships Phylum: Vertebrata (plesiomorphies and apomorphies) Class : Osteichthyes Order: Perciformes Taxonomy – theory & practice Nomenclature – naming of Family:Badidae taxonomic groups Genus: Badis Classification – organizing into taxa Species: badis Rank (International nomenclature code): Common name: Chameleon fish 1. Kingdom 2. Phylum/Division 3. Class 4. Order 5. Family 6. Genus Oreochromis niloticus L. 7. Species (subspecies) Allum cepa (L.) R. (botany) Classification of Fish  Three Classes of modern fish Agnatha – primitive jawless fish. e.g. lampreys and hagfish Chondrichthyes – jawed fished with cartilaginous skeleton e.g sharks, rays Osteichthyes – fish with bony skeletons e.g. milkfish, tilapia, tuna  Class Agnatha Characteristics  No jaws Primitive Lack true bones (cartilaginous skeleton) Scaleless skin Oral sucker Predators and filter feeders Found in both fresh and salt waters Some anadromous (fish live in the ocean mostly and breed in fresh water)  Class Chondrichthyes Characteristics “cartilage-fish” Skin covered with denticles, placoid scale 5-7 gill slits per side No swim bladder Internal fertilization Spiral valve intestines 5-7 gill arches  Sharks  Highly adapted to environment Carnivores or scavengers Possess keen sense of smell, large brain, good sight and Highly specialized mouth and teeth Body is heavier than water No swim bladder (buoyancy) Asymmetric tail Few venture in freshwater and been found in rivers  Class Osteichthyes Characteristics Largest section of the vertebrates with over 20,000 species worldwide Bony fishes because of calcified bones making much harder compared to cartilage bones Great maneuverability and speed Highly specialized mouth equipped with protrude jaws Has swim bladder for buoyancy  Fish General Anatomy 3 8 7 1 3 5 2 4 9 3 6 3 3 (1) Eye and its parts; (2) Operculum or gill cover; (3) Fins (median and paired); (4) Lateral line; (5) Mouth and its parts; (6) Genital papilla (anus and urinary pore); (7) Nare or nostril; (8) Scales; (9) Barbels Eyes  Well developed  Sharks have pupils that dilate and constrict (good eyesight)  Presence of eyelid (closes bottom to upward) Bony fishes do not have pupils and eyelids Mouth  The mouth parts of a fish will vary in size and may or may not contain teeth. The location of the mouth on a fish’s body can also give us a clue as to what may be the fish’s diet.  Nares  All fish possess a sense of smell.  Paired holes called nares, are used for detecting odors in the water, and are located on a fish’s snout.  Some fish, such as some shark species, catfish, and eels, have a very sharp sense of smell. Lateral Line  Running down the length of a fish’s body is the lateral line. It is made up of a series of microscopic holes located just under the scales of the fish.  One of the fish's primary sense organs, the lateral line can sense low vibrations in the water, and is capable of determining the direction of their source. Scales  Most fish have scales covering the length of their body. Scales protect fish from injury, much like skin on the human body. On top of these scales is a mucous covering known as the slime layer. Slime protects fish from bacteria and parasites in the water. Genital Papilla  Fish General Anatomy (Barbels in Catfish) 1 2 4 3 (1) Nasal barbel; (2) Mandibulary barbel; (3) Mental or Chin barbel; (4) Maxillary barbel Fish General Anatomy (Keel) Fish General Anatomy (Scutes) Fish General Anatomy  Fish General Anatomy Illicium Esca  Fish Fins 1 6 5 3 4 1 5 7 4 2 3 (1) Dorsal fin; (2) Pectoral fin; (3) Pelvic fin; (4) Anal fin; (5) Caudal fin;(6) Adipose fin; (7) Second dorsal fin  Functions of Fins Propulsion – most Fish Stabilization – sea Horse So that’s Stabilization – Bass, salmon what they Propulsion - Eels do Station keeping Propulsion Stabilization – most fish Finlet  Fish Fins 1. Paired Fins a. Pectoral fins b. Pelvic fins Fin Rays (Soft/Lepidotrichia) Branch ray Simple ray  Fish Fins 2. Median Fins a. Dorsal fin b. Anal fin c. Ventral(adipose and finlets) d. Caudal fin Fin Rays (Spine/Actinotrichia) Serrate spine Non-Serrate spine  Positioning of Pelvic Fin Abdominal – pelvic fins are attached midway down the belly Thoracic – pelvic fins are below the pectoral fins Jugular – pelvic fin is attached under the gills Positioning of Pelvic Fin Thoracic Jugular Abdominal Types of Caudal Fin Isocercal—last vertebrae modified (cods)  Gephyrocercal—”bridge tail” Dorsal and anal fins have grown around posterior end of fish. (Mola) Shapes of Caudal Fin Crescent or lunate Rounded Shapes of Caudal Fin Forked Truncated Shapes of Caudal Fin Emarginated Pointed Diversity of Mouth Mouth Positions Superior  Mouth Positions Sub-Terminal Inferior Terminal Mouth Diversity in Cyprinids  Mouth Shapes Rostral Mouth Shapes Elongated beak Mouth Shapes Short beak Mouth Shapes Tube  Mouth Shapes Retractable (protrusible) Suction disc BODY SHAPES  BODY SHAPES Fusiform – streamlined with pointed ends, shaped like plane, helps to lower frictional resistance, and allows to move through the water extremely fast Anguiliform/Attenuated – fish that are long, and skinny, fish slither like snakes, allows to maneuver into narrow openings and resist the force of current Globiform – fish that are almost round or lobe-shaped  BODY SHAPES Compressiform – fish that are laterally compressed, tall, thin body shape that allows fish to enter vertical crevices, allows for quick burst of speed and quick turns Depression – wide, flat body shapes that all fish rest on the bottom.  Scales in Fishes Dermal plates Microscopic to large, tissue thin to plate-thick, simple to complex, partial to complete, non-bony to bony, loosely deciduous to firmly attached Do All Fishes Have Scales? NO Clingfishes (Gobiesocidae) and Agnathans (lamprey, slime eels and hagfish) Why Do Fishes Have Scales?  Protection  Classification  Natural history  Derivatives Are All Scales the Same?  Freshwater eels- tiny embedded scales  Tunas- tiny scales  Coral snapper- medium-sized scale  Tarpon, Megalops cyprinoides- large scales  Indian Maheer, Tortor- 10 cm length How Old is a Fish Scale? Can a Fish Have More Than One Type of Scale? IN SOME Flounder and soles Can Scale Type Vary with Sex? IN SOME (Flatfish)  Types of Scale (Placoid)  Consists of flattened rectangular base plate which is embedded in the fish, and variously developed structures such as spines.  Composed of a vascular (supplied with blood) inner cone of pulp, a middle layer of dentine and a hard enamel-like outer layer of vitrodentine.  Examples: sharks, rays and relatives Types of Scale (Cosmoid) Consist of two basal layers of bone, a layer of dentine-like cosmine and an outer layer of vitrodentine. Lung fish (Family Ceratodidae)  Examples: lung fish and fishes belong to Family Ceratodidae  Types of Scale (Ganoid)  Have articulating peg and socket.  Consist of bony basal layer, a layer of dentine and an outer layer of ganoine (inorganic bone salt) Examples: bichirs (Polypteridae), bowfin (Amia calva), paddlefish (Polyodontidae), gars (Lepisosteidae) and sturgeons (Acipenseridae)  Types of Scale (Ctenoid)  Overlapping scales.  Has variously developed spiny posterior margin.  Consist of two main regions, a surface "bony" layer, composed of an organic framework impregnated largely with calcium based salts, and a deeper fibrous layer composed mainly of collagen.  Derived from ganoid scales that have lost the ganoine and thinned the bony embedded plate.  Ctenii – tiny, comblike projections on the exposed (posterior) edge of scales Paradise fish, Macropodus opercularis  Examples: male burbot (flounder and soles), trout, perch and paradise fish.  Types of Scale (Cycloid)  Overlapping scales.  Has circular , smooth margin.  Consist of two main regions, a surface "bony" layer, composed of an organic framework impregnated largely with calcium based salts, and a deeper fibrous layer composed mainly of collagen.  Derived from ganoid scales that have lost the ganoine and thinned the bony embedded plate. Red fire fish  Examples: red fire fish, flounder and soles (blind side), carp.  Swimbladder Gas filled bag that sits in a fish’s body cavity above its guts. By body volume, 5% in MF; 7% in FF Density (FW = 1.0, SW = 1.026, Fish = 1.076) Not all fish has swimbladder. SB of bony fish is neutrally buoyant at a particular depth 1 ATM (14.7 psi) increase for every 10 m depth  Sharks buoyancy Sizeable liver (25-30% of body) Squalene (low density, low specific gravity = 0.855) Cartilaginous skeleton (1.1 vs 2) Fins (for continuous swimming)  Buoyancy and Gaits Negative Buoyancy Advantage: Hold to bottom Disadvantage: Energy required to maintain in water column and move Density pushes down Im Back Energy to provide lift  Buoyancy and Gaits Neutral Buoyancy Advantage: Hold in position Disadvantage: Energy required to move up or down in water column Fun Weight not a problem Energy to provide lift  Buoyancy and Gaits Positive Buoyancy Advantage: Hold to surface Disadvantage: Energy required to maintain in water column and move (can’t dive) weight Buoyancy holds up Need Energy to dive  Negative Aspects Icthyotoxin – generally, any poison originating from fishes Ichthyosarcotoxin – poison found in flesh of fishes Ciguatera – caused by eating various marine fishes of tropical and subtropical areas. toxin: ciguatoxin, maitotoxin, scaritoxin, palytoxin affected fish: barracuda, snapper, moray eels, parrotfish, triggerfish, amberjacks effects: gastrointestinal and neurological, allodynia (severe) Negative Aspects Scombroid poisoning –caused by eating improperly preserved scombroid fishes toxin: histamine (Morganella morganii) (histidine = histamine) fish: mackerel, tuna, mahi-mahi, bonito, sardines, anchovies effect: severe allergic responses (symptoms can show minutes to 2 hours)  BIOACCUMULATION & BIOMAGNIFICATION Gambierdiscus toxicus  Negative Aspects Icthyohemotoxin – poison found in blood of fishes Icthyoacanthotoxin – poison secreted at the site of a venom apparatus such as spines, stings, or teeth of fishes Stonefish – rank no. 6 of the most venomous creatures  Icthyootoxin –poison found only in roe of fishes Tetradotoxin or tetrodox or TTX (neurotoxin) – the poison in viscera, liver, skin of Tetraodontiformes Puffer fish – rank no. 10 of the most poisonous creatures Other sources: porcupine fish, ocean sunfish, triggerfish Symptoms develop within 30 minutes (delayed up to 4 hours)  Positive Aspects Fishes as biological control Scientific uses of fishes Recreational fisheries The aquarium trade Fish culture  Taxonomic Methods A. Morphometric traits - any standard measurement that can be made on a fish i.e. snout length, total length, width of eye, length of jaw in body length, etc.  Taxonomic Methods B. Meristic traits - any trait that can be counted i.e. vertebrae, fin rays, scale rows, lateral line pores, branchiostegal rays  Morphometric Characteristics Counting and measurement for identification dorsal height Total length Pre-dorsal length D. Soft fin rays Circum-peduncular scale Lateral-line scale Transverse scale Head length Anal fin base L Point-to-point measurements Standard length  Morphometric Characteristics Head length Eye length Anal fin base length  Morphometric Characteristics Body depth Standard length Caudal peduncle length Total length  Morphometric Characteristics (Exceptional cases) Position of tail spine Fork length Disc length Maximum width Total length Meristic Characteristics Examples of Meristic Characteristics: 1.No. of dorsal rays/spines 2.No. of anal rays/spines 3.No. of pectoral fin unbranched/branched rays 4.No. of lateral line scales (upper and lower) 5.Transverse line scales 6.Caudal peduncle scales 7.Cheek scales 8. Total gill rakers 9.No. of outer teeth on the lower jaw and upper jaw Meristic Characteristics Lateral-line scales  Taxonomic Methods C. Anatomical/morphological characteristics – descriptions of morphological (external) and anatomical (internal) features (not measurements or counts) i.e. shape or lateral line, special features (lung, etc), secondary sexual characters, position of fins and barbels  Taxonomic Methods D. Molecular phylogenetics - examination of traits at the molecular level Cladogram - displays the inter-relatedness of taxonomic groups, divides them by shared or not- shared traits in a dichotomous manner, show transition from more primitive to more advanced Phylogenetic tree - as above + includes passage of time between branch points In cladogram, branch lengths are not necessarily proportional to the evolutionary time between related organisms or sequences. Cladogram v.s. phylogenetic tree Taxonomic Methods  Phylogeny of Fishes A. Split 1: Lacking true vertebrae vs.Vertebrata 1. Lacking true vertebrae – hagfish 2. Vertebrata - all others Lamprey: Petromyzontiformes B. Split 2: Agnatha vs. Gnathostomata 1. Agnatha - lacking jaws (lamprey) 2. Gnathostomata - bearing jaws (all others) Hagfish: Myxinidae  Phylogeny of Fishes C. Split 3: Chondrichthyes vs. Osteichthyes 1. Chondrichthyes - cartilaginous fishes a. Holocephali - chimeras and ratfishes, upper jaw and skull fused b. Elasmobranchii - sharks, skates and rays 2. Osteichthyes - bony fishes (all others)  Phylogeny of Fishes D.Split 4: Sacropterygii vs. Actinopterygii 1.Sacropterygii - lobe-finned (coelacanth, lungfish, ancestors of all tetrapods) 2.Actinopterygii - ray-finned (all others)  Phylogeny of Fishes E.Split 5: Chondrostei vs. Neopterygii 1.Chondrostei - ancient fishes (sturgeon, paddlefishes) a.secondarily cartilaginous b.spiral valve intestine (as in skarks) 2.Neopterygii - modern fishes (all others)  Phylogeny of Fishes F. Split 6: non-teleosts vs. Teleostei 1. Non-teleosts - including gars and bowfins – formerly grouped as Holostei, which turned out to be paraphyletic a. abbreviated heterocercal tail b. ganoid scales (in gars, bowfins have cycloid scales) 2. Teleostei - including the majority of ray finned fishes a. homocercal tail b. cteniod or cycloid scales