Chordata 2024-2025 PDF

Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. Phylum: Chordata Chordates include 45,000 species. At some time during their life, all chordates have four basic characteristics. a. Notochord It is a supporting rod located dor...

Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. Phylum: Chordata Chordates include 45,000 species. At some time during their life, all chordates have four basic characteristics. a. Notochord It is a supporting rod located dorsally just below the nerve cord. It is replaced by the vertebral column in vertebrates. b. Dorsal Hollow Nerve Cord This cord contains a fluid-filled canal. In vertebrates, this is the spinal cord, and it is protected by vertebrae. c. Pharyngeal Pouches -These openings function in feeding, gas exchange, or both. -They are seen only during embryonic development in most vertebrates. -In invertebrate chordates, fish, and amphibian larvae, they become functioning gills. -In terrestrial vertebrates, they are modified for various purposes. In humans, the first pair of pouches becomes the auditory tubes, the second become tonsils, and the third and fourth pairs become the thymus and parathyroid glands. d. A post-anal tail Extends beyond the anal opening; in some, this only appear in embryos. 1- Sub phylum: Invertebrata Invertebrate Chordates The notochord persists and is never replaced by the vertebral column in these species. A- Cephalochordata (Lancelets, Amphioxus sp.) - About 23 species of lancelets are in genus Branchiostoma. An elongated, lance-shaped body resembles the lancelet, a two-edged surgical knife. - They inhabit shallow coastal waters; they are filter feeders partly buried in sandy substrates. -They feed on microscopic particles filtered from a stream of water that enters the mouth and exits through gill openings. 1 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. -The notochord extends from head to tail, as the name “Cephalochordata.” - They possess segmented muscles. -The dorsal nerve cord has several branches. B- Urochordata (Tunicates) - It contains 1,250 species of tunicates. - Adults have a body composed of an outer tunic; an excurrent siphon squirts out water when it is disturbed. - The larvae are bilaterally symmetrical and have the four chordate characteristics. - The larvae undergo metamorphosis to develop into adults. - Water passes into a pharynx and out numerous gill slits. - Cilia lining the inside of the pharynx create a current. Microscopic particles adhere to a mucous secretion in the pharynx and are then eaten. - The urochordate larva may have been ancestral to vertebrates. 2 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. 2- Subphylum: Vertebrata Vertebrate Chordates -The 43,700 species of vertebrates are in this subphylum. -Vertebrates have all four chordate characteristics at some time during their lives. -The embryonic notochord is replaced by a vertebral column. -The vertebral column is individual vertebrae that surround a dorsal hollow nerve cord. The vertebral column is part of a flexible, strong endoskeleton that is also evidence of segmentation. -The vertebrate skeleton is a living tissue (either cartilage or bone) that grows with the animal, muscles permit rapid and efficient movement. -A skull at the main axis of vertebrate endoskeleton; contains the brain. -There are complex sense organs like the eyes that developed as outgrowths of the brain and the ears—equilibrium devices in water—function as sound-wave receivers in land vertebrates. -Vertebrates possess a complete digestive system and a large coelom. -The circulatory system is closed and the blood is contained within blood vessels. -Respiration by gills or lungs that provide efficient gas exchange. -The kidneys efficiently excrete nitrogenous waste and regulate water. -Reproduction is usually sexual with separate sexes. 3 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. I. Fishes - Fishes are aquatic, gill-breathing vertebrates that usually have fins and skin covered with scales. - They were filter feeders also able to move water through their gills by muscular action. The Agnatostomata (Class: Cyclostomata) Jawless Fishes 1. Jawless fishes are agnathans; 63 species belong to class: Agnatha. 2. Lampreys and hagfishes are modern jawless fishes, and they lack a bony skeleton. 3. They have smooth non-scaly skin. 4. They have cylindrical bodies and are up to a meter long. 5. Hagfishes are scavengers feeding on soft-bodied invertebrates and dead fishes. 6. Many lampreys are filter feeders similar to their ancestors. 7. Parasitic lampreys have a round muscular mouth equipped with teeth; they attach themselves to fish and suck nutrients from the host’s circulatory system. The Gnathostomata A. (Class:Chondrichthyes) Fishes with Jaws - Gnathostomates are animals with jaws. Cartilaginous Fishes (Class: Chondrichthyes) 1. 850 species of sharks, rays (Stingrays, Sawfish rays) and skates. 2. They have a cartilaginous skeleton rather than bone. 3. Five to seven gill slits are on both sides of the pharynx; No gill covers found on bony fish. 4. Their body is covered by epidermal placodes (tooth-like) scales. 5. The teeth of sharks are enlarged scales; there are many rows of replacement teeth growing behind the front teeth. 4 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. 6. They have three well developed senses to detect electric currents in water, pressure (a lateral line system), and smell. 7. The largest sharks are filter feeders, not predators; the whale sharks eat tons of crustaceans. 8. Most sharks are fast, open-sea predators; a great white shark eats dolphins, sea lions and seals. 9. Rays and skates live on the ocean floor; their pectoral fins are enlarged into winglike fins and they swim slowly. Stingrays have a venomous spine. Electric rays feed on fish that have been stunned with an electric shock that may reach over 300 volts. B. (Class Osteichthyes) Bony Fishes 1. About 20,000 species of bony fishes are in this class. Ex: Salmon, Trout, Eels 2. Bony fishes have a bony skeleton; most are ray-finned with thin, bony rays supporting the fins. 3. The ray-finned fishes include our familiar fishes. a. They vary from filter feeders to predaceous carnivores. b. Their skin is covered by scales formed of bone. c. The gills are covered by an operculum. d. The swim bladder is a gas-filled sac whose pressure can be altered to regulate buoyancy and depth. e. Fish sperm and eggs are usually shed into water. f. For most fish, the fertilization and embryonic development occur outside the female’s body. 5 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. 6 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. II. Amphibians 1. They are tetrapods, they have four limbs. 2. Land animals use limbs to support their body. 3. 3,900 species of amphibians belong to Class: Amphibia. 4. Amphibians have diversified during the "Age of the Amphibians" (Carboniferous period). 5. Diversity of Amphibians a. Modern amphibians include three groups: (frogs & toads), ( salamanders & newts), and the caecilians. b. Salamanders and newts have a long body and tail, and two pairs of legs; they resemble the earliest fossil amphibians. Their S-shaped movements is similar to fish. Salamanders and newts are carnivorous, feeding on insects, snails, etc. Salamanders practice internal fertilization; the males produce a spermatophore that females pick up with the cloaca. c. Frogs and toads are tailless as adults; the hind limbs are specialized for jumping. Frogs and toads have the head and trunk fused; frogs live near or in fresh water while toads live in damp places away from water. d. Caecilians are legless; most burrow in soil and feed on worms, etc. e. Reproduction involves a return to the water: 1) They shed eggs into the water for external fertilization. 2) Generally, amphibian eggs are protected by a coat of jelly not by a shell. 3) The young hatch into aquatic larvae with gills (tadpoles). 4) The aquatic larvae usually undergo metamorphosis to develop into a terrestrial adult. 7 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. 7. Anatomy and Physiology of Amphibians a. A tongue is used for catching prey. b. The eyelids keep their eyes moist. c. Amphibian ears are adapted for detecting sound waves; in turn, the larynx produces calls. d. The brain is larger than of fishes; their cerebral cortex is more developed. e. Respiration, they usually have small lungs in addition to gas exchange across skin. f. A three-chambered heart with a single ventricle pumps mixed blood before and after it has gone to the lungs. g. Amphibian skin is thin, smooth, non-scaly, and contains numerous mucous glands; it plays an active role in osmotic balance and respiration. h. Some skin glands secrete poisons; those tropical species often have brilliant warning coloration. i. Amphibians are ectothermic, regulate body temperature depending on the environment. j. If winter temperature drops too low, they enter in hibernation. 8 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. III. Reptiles 1. Reptiles were the first vertebrates to practice internal fertilization and to lay eggs protected by a leathery shell. 2. The egg contains an extra-embryonic membrane, called the amnion. They are not part of the embryo and are disposed of after development. It protects the embryo, remove nitrogenous wastes, and provide oxygen, food, and water. The amnion is filled with fluid to provide a “pond” for embryo to develop. 3. About 6,000 species of reptiles are in the class Reptilia. 4. Reptiles evolved from amphibians during Permian period. 5. The first reptiles (stem reptiles) gave rise to several lineages; each was adapted to a different way of life. a. The pelycosaurs or sail lizards are related to therapsids, mammallike reptiles ancestral to mammals. b. The ichthyosaurs returned to aquatic environments; and plesiosaurs had a long neck. c. The pterosaurs of the Mesozoic era had a keel for attachment of flight muscles and air spaces in bones to reduce weight. 6. Dinosaurs varied in size and behavior; some had a bipedal stance and gave rise to birds. 7. Reptiles dominated earth for about 170 million years during the Mesozoic era. 8. Luis and Walter Alvarez proposed the impact theory of dinosaur extinction. a. A large meteorite or comet at the end of the Cretaceous period could have set off earthquakes and fires, raising enough dust and smoke to block out the sun. b. An iridium layer, a mineral common in meteorites, occurs in rocks at the end of this period. 9. Diversity of Reptiles a. Most reptiles today live in the tropics or subtropics; lizards and snakes live on soil; turtles, crocodiles and alligators live in water. c. Crocodiles and alligators are largely aquatic, feeding on fishes and other animals. d. Turtles have a heavy shell fused to the ribs and to the thoracic vertebrae. Turtles lack teeth but use a sharp beak. Sea turtles must return to lay eggs onshore. e. Lizards have four clawed legs and are carnivorous. Marine iguanas on the Galapagos are adapted to spend long times in the sea. Chameleons live in trees, have a long sticky tongue to catch insects, and change color. f. Snakes evolved from lizards and lost legs as an adaptation to burrowing. Their jaws can dislocate to engulf large food. A tongue collects airborne molecules to transfer them to Jacobson’s organ for tasting. Some snakes are poisonous and have special fangs to inject venom. g. Reptiles have a thick, scaly skin that is keratinized and is impermeable to water and requires several molts a year.. h. Reptile lungs are more developed than in amphibians. 9 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. i. They have a nearly four-chambered heart, except in the crocodile it is completely four-chambered. j. Well-developed kidneys excrete uric acid; therefore, less water is lost in excretion. k. Reptiles are ectothermic. They require a fraction of the food per body weight of birds and mammals. They are behaviorally adapted to warm their body temperature by sunbathing. 10 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. IV. Birds 1. About 9,000 species of birds are in the Class: Aves. 2. Birds lack teeth and have only a small tail. Related to reptiles by scales on their legs, claws on their toes, and a horny beak. They also lay an egg, but in hard-shell not a leathery-shell. 3. Bird anatomy is closely related to its ability to fly. Bird forelimbs are modified as wings for flying with hollow, light bones laced with air cavities. 4. A beak composed of keratin has replaced jaws. 5. A keeled breastbone anchors muscles used in flight. 6. Bird respiratory air sacs are extensive, even extending into some larger bones, proper oxygenation of blood and efficient supply of oxygen to muscles needed for flight. 7. Birds possess a four-chambered heart; this double-loop circulatory system separates oxygen-rich and oxygen-poor blood. 8. Birds are endothermic; they have ability to maintain a constant, high body temperature. Homeothermy enables an animal to be active in cold weather. Feathers have evolved for insulation and then became adapted for flight. 9. Flight requires well-developed sense organs and nervous system. Birds have very acute vision and excellent muscle reflexes. Bird migration allows use of widespread food sources. 10. Bird classification is based on beak and foot types, and some on habitats and behaviors. 11 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. 12 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. V. Mammals 1. Over 4,800 species of mammals belong to the class: Mammalia. 2. Mammals evolved during the Mesozoic era from therapsids, extinct mammal like reptiles. 3. The mammal skull is bigger, their teeth are differentiated into molars and premolars, and the vertebral column provides more movement. 4. True mammals appeared during the Jurassic period, as the first dinosaurs. a. The first mammals were small, about the size of mice. b. Some of the earliest mammalian groups were marsupials. c. Placental mammals evolved later to occupy habitats vacated by dinosaurs. 5. The chief characteristics of mammals are hair and mammary glands. 6. Mammals are endothermic; they maintain a constant body temperature. 7. Hair provides insulation against heat loss and allows mammals to be active in cold weather. 8. Gas exchange is efficiently accomplished by lungs. 9. Mammals possess a four-chambered heart and a double-loop circulatory system. 10. Mammary glands enable females to feed young without deserting them to obtain food. Nursing creates a bond between mother and offspring to ensure parental care while the young are helpless. In most mammals, the young are born alive after a period of development in uterus. Mammals That Lay Eggs - Monotremes are mammals that have a cloaca and lay hard-shelled amniote eggs. - They are represented by the duckbill platypus and the spiny anteater of Australia. - A female duckbill platypus lays her eggs in a burrow in the ground where she incubates them. - The spiny anteater has a pouch formed by swollen mammary glands and muscle. 13 Dr. Hossam Zahran  Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. Mammals That Have Pouches - Marsupials begin development inside the mother’s body but are then born in a very immature state. The newborns crawl up into a pouch on their mother’s abdomen. Inside a pouch they attach to the nipples of the mother’s mammary glands and continue to develop. - Today, most marsupials are found in Australia where they underwent adaptive radiation for several million years without competition from the placental mammals, only introduced recently. Mammals That Have Placentas - Placental mammals use a placenta as an organ of exchange between maternal and fetal blood. The placenta supplies nutrients to and removes wastes from the blood of developing offspring. A placenta also allows a mother to move about while the baby develops. The placenta enables young to be born in a relatively advanced stage of development. - Placental mammals are very active animals; they possess acute senses and a relatively large brain. - The brains of placental animals have cerebral hemispheres proportionately larger than other animals. - The young go through a long period of dependency on their parents after birth. - Today, placental mammals populate all of the continents except Antarctica. - Most are terrestrial, but some are aquatic, and bats can fly. 14 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. Mammals Classification Classification of mammals is based on mode of locomotion and the method of obtaining food. 1.The order Perissodactyla includes 17 species of horses, zebras, tapirs, and rhinoceroses and the order Artiodactyla includes 185 species of pigs, cattle, deer, buffaloes, giraffes, etc. Both orders are hoofed animals. They have elongated limbs adapted for running across open grassland. They are herbivorous and have large grinding teeth. 2.About 270 species are in order Carnivora. Carnivores include the dogs, cats, bears, raccoons, and skunks. The canines of meat eaters are large and conical. Aquatic carnivores such as seals and sea lions must return to land to reproduce. 3.The order Primates contains 180 species of lemurs, monkeys, gibbons, chimpanzees, gorillas, and humans. - Typical primates are tree-dwelling fruit eaters; some are ground dwellers. - Their digits have nails, not claws; the thumb is more opposable. - Primates, particularly humans, have well-developed brains. 4.The order Cetacea includes about 80 species of whales and dolphins. - They lack substantial hair or fur. - Blue whales are the largest animal ever to live on this planet are whales that strain plankton from the water. Toothed whales feed on fish and squid. 5.The order Chiroptera contains 925 species of nocturnal bats. Wings are layers of skin and connective tissue stretched between the elongated bones of all fingers but first. Many species use echo-location to locate their usual insect prey. Some bats also eat birds, fish, frogs and plant tissues. 6.The order Rodentia contains rodents (e.g., mice, rats, squirrels, beavers, and 15 Dr. Hossam Zahran Department of Applied Entomology &Zoology Class: 1st batch Zoology (11101) 2024-2025. porcupines). This is largest order with 1,760 species. Rodents have incisors that grow continuously. Most rodents eat seeds but some are omnivorous or eat mainly insects. 7.Only two species are in order Proboscidea: the elephants. - Upper lip and nose are elongated and muscularized forming a prehensile trunk. - They are herbivores and are largest living land mammals. 8.Order Lagomorpha includes 65 species of rabbits, hares, and pikas. - They resemble rodents but have two pairs of continuously growing incisors. - Their hind legs are longer than their front legs and they are herbivores. 16 Dr. Hossam Zahran