Phylum Chordata

1. Phylum Chordata • A Chordate is an animal that has 4 specific characteristics during their life cycle: • 1- Dorsal, hollow nerve cord • 2- Notochord – a long supporting rod that runs through the body below the nerve cord • 3- Post anal tail • 4-Pharyngeal pouches (gill slits)

2. 1- A Dorsal, Hollow Nerve Cord • This is a sheath of large nerve cells • These nerve cells are somewhat like stem cells in they may play an important role in other nerve cells that develop • Example: certain motorneurons are affected by the absence of these cells in embryonic development • In higher organisms, the actual “spinal cord” is surrounded by this hollow covering.

3. 2- A Notochord • The notochord is a strong structural part of the organism • It is located dorsally from the gut (endoderm and coelom) • It is made of cartilage or bone • It is the spine, or vertebral column

4. 3- A Post Anal Tail • Post means it is located posterior to the anus, or behind the anus • It is an extension of the notochord, and made of cartilage or bone

5. 4- Pharyngeal pouches • These are located at the pharynx, or throat, of a chordate • They develop into the gills of fish and juvenile amphibians • In aquatic reptiles, birds and mammals, they close during embryonic development and become the throat, while the nasal passageways develop

6. Subphyla of the Phylum Chordata • The Nonvertebrates: • Sub Phylum Urochordata tunicates or “Sea Squirts” • Sub Phylum Cephalochordata – lancelets • These are very simple chordates without spines • All are aquatic

7. Subphyla of the Phylum Chordata • The Vertebrates • Sub Phylum Vertebrata– cartilaginous and bony fish, amphibians, reptiles, birds, mammals • These are chordates with spines of cartilage or bony tissue

8. Vocabulary • Body temperature control: • Ectotherm – animals that rely on behavior and interactions with the environment (Cold-Blooded) • Endotherm– animals that generate their own body heat and control temp. from within (Warm-Blooded)

9. VocabularyEgg to Juvenile Method: • Oviparous – Eggs hatch outside the female body • Ex: Most Fish • Ovoviviparous– Eggs develop inside the female body and the young are live-born • Ex: Some Sharks) • Viviparous – bear live young that are nourished directly by the mother’s body as they develop. • Ex: Whales, Otters

10. Vertebrates – Agnathans(jawless fish) • Examples: Lamprey; Hagfish • Body Plan: snake-like, no scales, no paired fins, no true teeth or jaws • Skeleton Type: fibers and cartilage • 2 chambered • Temperature control: ectotherm • Respiration: gills • Reproduction: sexually-external/ internal fertilization (oviparous) • Importance:lamprey are parasites and hagfish are decomposers that feeding on dead or decaying fish)

11. Vertebrates – Class Chondrichthyes • Examples: Sharks, Rays, Skates • Chondros(Gk = cartilage) • Body Plan: large curved tails, torpedo-shaped body, pointed snout, moveable jaw, placoid (rough as sandpaper)scales • Skeleton Type: cartilage • 2 chambered • Temperature control: ectotherm • Respiration: gills • Reproduction: sexually- external/internal fertilization (oviparous/ovoviviparous/some viviparous) • Importance: predators in the food chain

12. As the front row of shark teeth are worn out, new teeth are continually replacing them. A shark goes through 20,000 teeth in its lifetime!! A skate is shown in the top picture; a stingray below

13. Vertebrates – Osteicthyes(bony fish) • Examples: goldfish, perch, bass, trout • Body Plan: lateral line (use this to sense motion of other fish nearby), swim bladder (internal, gas-filled organ that adjusts buoyancy), scales • Skeleton Type: hard, calcified tissue called bone • 2 chambered • Temperature control: ectotherm • Respiration: gills • Reproduction: sexually- external fertilization(97% are oviparous) • Importance: prey in the food chain, fishing industry

14. Bony Fish Types • Saltwater • Strictly live in water with dissolved salt content near seawater, about 35 ppt in the open ocean • Must regulate the loss of freshwater out of their bodies as natural osmosis and diffusion seek to balance salt concentrations within and surrounding their bodies • Ex: marlin, mullet, snapper; flounder • Brackish water • Require salinities between 35 ppt and freshwater • Many marine fry are hatched in brackish water then migrate to open oceans as they mature • Ex: fry; sheepshead, croaker • Freshwater • Strictly live in freshwater • Must regulate the increase of freshwater into their bodies as natural osmosis and diffusion seek to balance salt concentrations within and surrounding their bodies • Ex: blue catfish; bluegill, hybrid bass

15. More Types of Fish • Catadromous • These fish hatch in marine waters and then migrate into freshwater to spend adulthood • They return to marine waters to spawn • Ex: Eels are the most common fish to do this, and the Sargasso Sea, near the southern part of the Atlantic Gyre, is their famous spawning ground • Anadromous • These hatch in freshwater and then migrate into marine waters to spend adulthood • They return to freshwater to spawn, and then usually die • Ex: Salmon, shad, smelt and sturgeon are examples.

16. Things you must know: • Fish External Anatomy • All fins • Lateral line • Scale Type • Fish Internal Anatomy • Fish Organ Systems • Fish Morphology • Body Shape that indicates ecological niche • Fish Behaviors • Mating, Territoriality, Parenting • Identifying and “Keying Out” Fish • What class are they in

17. Vertebrates - Reptilia • Examples: snakes, lizards, turtles & tortoises, crocodiles • Body Plan: dry, leathery skin, thick scales made of karatin (smooth or rough), terrestrial, amniotic eggs (shell & membrane so egg can develop out of water) • Skeleton Type: hard, calcified tissue called bone • 3 chambered except crocodiles with 4 chambered • Temperature control: ectotherm • Respiration: lungs • Reproduction: sexually- internal fertilization – eggs laid on land(most oviparous/ some ovoviviparous) • Importance: control rat populations, medical use/research, clothing industry

18. Turtles make a nest and lay their eggs on land. Snakes are carnivorous and stretch their jaws to consume their prey whole. The sex of a crocodile is determined by temperature, with males produced at 88 F, and females produced at 80 F and 93 F.

20. Loggerhead Turtle • Carettacaretta- one of the largest, most abundant sea turtles

21. Kemp’s Ridley Turtle • Lepidochelyskempii - Endangered, smallest of sea turtles, feeds mostly on crabs

22. Leatherback Turtle • Dermochelys coriacea - largest turtles on Earth, growing up to seven feet long and exceeding 2,000 pounds

23. Sea Turtles • Bodies enclosed in a carapace (top shell) that is fused to their backbone

24. Cannot retract their head into their shell • Legs are modified into flippers for swimming

25. Migrate long distances to reproduce • 7-8 species • Most live in warm waters

26. Do not have teeth, but have strong jaws

27. Females lay 100-160 eggs in a nest that hatch about 60 days later

28. Green turtle is hunted mostly for meat and cartilage for turtle soup • TEDS – turtle exclusion device mandated by US government for shrimp nets

30. Nesting • Very little is known why sea turtles nest on some beaches, and not on others • Most females return faithfully to the same beach each time they nest

31. Females nest usually at night • “false crawl” – occurs when female turns back and decides not to nest

32. Females appear to “shed” tears as they lay, secreting salt that has accumulated in her body • Covers with rear flippers and disguises the nest

33. Incubation & Emergence • About 60 days • The hotter the sand, the faster they hatch • Warmer sand – more females • Cooler sand – more males

34. Hatchlings use a temporary, sharp egg-tooth called a “caruncle” to break open the shell • Caruncle then falls off

35. Digging out of the nest is a group effort that takes days • Emerge from nest in a group

36. Orient themselves to the brightest horizon • Only about 1 in 1000 survives to adulthood

37. Vertebrates – Amphibia(“double-life”) • Examples: frogs, Toads, newts, salamander • As larvae usually live in water and as adult live on land • Body Plan: moist skin with mucus glands, lack scales/claws, undergo metamorphosis • Skeleton Type: hard, calcified tissue called bone • 3 chambered • Temperature control: ectotherm • Respiration: young=gills adult=lungs • Reproduction: sexually- external fertilization(oviparous) or internal (salamanders) • Importance: control insect populations, medical/ pharmaceutical use, food source (frog legs) in India/Asia

38. Frog Metamorphosis

39. Vertebrates – Aves (birds) • Examples: chickens, penguins, cardinals, ostrich • Body Plan: feathers of protein/keratin (flight/warmth), two legs covered in scales, front limbs modified into wings, thin hollow bones (helpful for flying) • Skeleton Type: hard, calcified tissue called bone • 4 chambered • Temperature control: endotherm (can generate own body heat) • Respiration: lungs, includes passageways of air through the skeleton • Reproduction: sexually- internal fertilization - oviparous • Importance: control insect populations, food source, clothing, bedding, hunting purposes

40. Aquatic Birds have special adaptations… • Their feathers are highly resistant to being wetted • They usually have higher oil production than other birds from glands at the base of the tail • The oil is applied to the feathers during preening • Preening is birds grooming activity; they run their beak through their feathers to straighten and comb them • During preening oil is spread lightly over feathers to help keep them water resistant • Dry feathers • Keep birds warm when in aquatic sites • Are easier to use for flight (think about a paper airplane that is dry vs. one that is wet!)

41. More special adaptations… • Aquatic birds also have special appendages… • Feet are webbed for swimming • Legs may be longer to wade in water • Long toes spread out to distribute weight in mud • And their beaks are modified for grasping wet, slippery prey • Hooked tips, the huge “baskets” of pelicans, spear-like points in herons, cranes and egrets; filters of flamingos • Beaks modified into bills for duck- and goose-like creatures • For sifting worms and arthropods from mud, or for catching fish underwater

42. Vertebrates - Mammalia • Examples: cats, whales, gorillas, zebras, humans • Body Plan: mammary glands (produce milk to nourish the young), have hair, breathe air, bear live young • Skeleton Type: hard, calcified tissue called bone • 4 chambered • Temperature control: endotherm(can generate own body heat) • Respiration: lungs • Reproduction: sexually- internal fertilization (viviparous) • Importance: food, hunting, clothing, medical research, pets

43. Mammalia Reproduction Diversity • Monotreme– “egg-laying mammal”; like reptiles except after eggs hatch the young is nourished by mother’s milk • Only 3 species exist: duckbill platypus, 2 spiny anteaters • Marsupial – bear live young that complete their development in an external pouch • Kangaroos, koalas, wombats • Placental – nutrients, O2, CO2, wastes are exchanged b/n embryo and mother through placenta • Elephants, rabbits, humans