Phylum Chordata

1. Phylum Chordata Vertebrates

2. Phylum Chordata • All members of the phylum (the most advanced of the animal phylum) have a stiffening notochord. • Notochords are stiff rods of connective tissue. • The also have a tubular dorsal nervous system and gill slits behind the oral opening at sometime during their development. • The notochord serves as a rigid support and a foundation for muscles and bone. • 5% of 45,000 species of chordates lose their notochord as they develop. • These are invertebrate chordates. • 95% retain the notochord or the vertebral column that forms around it. • These are called Vertebrate Chordates.

3. Fertilization • Internal • Oviparous (develop in egg that has been laid) • Viviparous (live birth; young nourished via placenta) • Ovoviviparous (live birth from eggs hatched as laid; young nourished by egg yolk) • External– female lays unfertilized egg; sperm fertilizes after egg laid • Reproduction • Amniote – vertebrates that have an amnion • Anamniote - vertebrates that lack an amnion, or extraembryonic membrane that surrounds the embryo and encases it in amniotic fluid

4. Classification of Groups Within the Phylum Chordata • Phylum Chordata • Subphylum Vertebrata: • Class Agnatha (jawless fish) – Hagfish; lamprey • Class Chondrichthyes (cartilage skeleton) – Sharks; Rays; Skates • Class Osteichthyes (bony skeleton) – tuna; seahorse; puffers • Class Amphibia – frogs; salamanders • Class Reptilia – crocodiles; turtles; snakes • Class Aves – gulls; penguins; terns • Class Mammalia – Whales; seals

5. Fish • Vertebrates • Live in water • 2 chambered heart • Possess gills • Have fins • There are more species of fish and more individuals than species and individuals of all other vertebrates combined. • Range in size form 10 millimeters to over 20 meters (.4 inches to 60 feet) • Weigh from 0.1 gram to 41,000 kilograms. (.004 ounces to 45 tons) • Ectotherms – cold blooded (can not maintain a steady internal temperature) • 40% of species live all or part of their life in freshwater. • 60% live exclusively in salt water.

6. Structure & function nostril- smell, no respiration mouth- teeth slant back, tongue for touch not taste operculum- protect gills pectoral fin- swim forward and stay in one spot pelvic fin-steer and balance while resting, act as oars for swimming, backward anal fin- balance caudal fin- strong forward thrust dorsal fin- upright swimming, protection lateral line- acute sense of low frequency vibrations and pressure

7. Coloration • countershading- blue top, white bottom • ex. Shark • disruptive coloration- strips to blend • ex. clown fish • aggressive mimicry-blending • ex. stone fish • territorial- brightly colored • ex. Garibaldi • social status- difference within a species to denote rank or sex • ex. damsel fish • false advertising-eye spots on tail • ex. angel fish

8. Protection spines-lion fish stingers-rays distenable body-puffers teeth-sharks plates-sturgeon fish freezing- pipefish rapid swimming- wings-flying fish mucus-hagfish

9. Special features • bioluminescence-light organs • ex. lantern fish • barbells-whisker sensory organs on the mouth • ex. catfish • anglers-lures that entice fish to come closer • ex. anglerfish • electricity- ability to generate electricity • ex. torpedo ray

10. Class Agnatha • (a = lacking; gnathos = jaw) • Examples – Hagfish and Lampreys • 75 species Characteristics • External fertilization • Lack jaws • No paired appendages/fins • Have gill slits • Have openings to slime glands • Have round sucking mouths surrounded by organs sensitive to touch • Tails are flattened • Lack swim bladder • Eye are covered by thick skin • Ectothermic • anamniote

11. Hagfish: • Pink • Live in colonies • Marine only • Feed on the inner tissues and internal organs of its prey • Lamprey; • Have a toothed, funnel-shaped mouth • Freshwater and marine • Rasps through scales and skin to get nutrients from blood

12. Class Chondrichthyes • (chondros = cartilage; ichthys = fish) • True bones do not exists. • jaws with teeth • Anamniote • 800 species • paired fins • Examples-Sharks and Rays • Tend to be larger than either Agnathans or bony fish. • Only a small fraction of all fish species are members of this group. • Nearly all are marine; a few species will inhabit estuaries and very few are found in fresh water. • Skates have flattened bodies with spreading pectoral fins – They move by flapping of these fins. • oviparous

13. Rays: • Ovoviviparous • Some have a defensive barb on their tail • Some grow to 7 meters across (giant Manta) • Some have the ability to shock their prey. • smooth skin • Do not have gas bladders, so slightly negatively buoyant; they sink if they stop swimming. • flattened bodies with spreading pectoral fins • move by flapping of fins

14. Sharks: • 80% are less than 2 meters long • Not very intelligent • Hunt prey by vibrations in the water and also by smell. • Do not have gas bladders, so slightly negatively buoyant; they sink if they stop swimming. • Covered with a tooth-like placoid scale. • Largest – Whale shark; 18 meters (60 feet), 41,000 kilograms (90,000 pounds); feed on plankton • Carcharodon (Karcharos = sharp; odontos = tooth) Great White Shark; 7 meters, 1,400 kilograms • Other “dangerous” species: Mako; Tiger; Hammer head • ovoviviparous

21. Class Osteichthyes • (osteum = bone; ichthys = fish) • 27,000 + species • Ovoviviparous & viviparous & external • Anamniote • Paired fins • Success due to light, hard, strong skeleton that supports them. • Most numbers and successful of all vertebrates. • Representatives of this class are found in every marine habitat. • 90% of all fish belong to the Class Osteichthyes and the Order Teleostei (teleos = perfedt; osteon = bone) • perch, tuna, flounder,etc. • a gas filled swim bladder to help maintain neutral buoyancy. • independently movable fins for well controlled swimming. • capable of great speed for pursuit or avoidance of predators. • effective camouflage. • social organization • orderly pattern of migration. • ability to cluster together in defensive schools. • Over 77 million tons of bony fish are taken annually form the ocean for consumption.

22. Special features • bioluminescence-light organs • ex. lantern fish • barbells-whisker sensory organs on the mouth • ex. catfish • anglers-lures that entice fish to come closer • ex. anglerfish • electricity- ability to generate electricity • ex. torpedo ray

23. Movement, Shape & Propulsion • A fish’s resistance to movement (drag) is determined by the frontal area, body contour and surface drag. • Drag increases geometrically with increasing speed. Faster swimming fish must be highly modified to minimize drag. • The most effective antidrag shape is a tapering torpedo-like body plan. • This shape produces minimum drag when they are: • circular in cross-section • greatest width is ¼ the length • the point of max width occurs about 2/5 the distance from the leading tip

24. Thrust come from a combines effort of the body and fins. • Muscles in slender flexible fish (eels) create S-shaped waves along the body. The body pushes against the water. • This movement is not efficient; body length to width ratio must be too high (this increases the surface area that creates drag) • More efficient forms have shorter less flexible bodies that undulate more rapidly and a hinged tail to transfer muscular energy to the water. • How Efficient? • In the fastest fish 60-80% of muscle force delivered to the tail results in forward movement. • Marlin & swordfish can travel 33 meters/second (75 mph)

26. Maintenance of Level • The density of a fish’s tissue is greater than surrounding water. • This difference is offset by propulsive forces and by buoyant gas or fat-filled bladders (swim bladder) • The quantity of gas is controlled by: • secretion and absorption of gas from the blood • muscular contraction of the bladder. • Fast predators lack a swim bladder. The volume would have to change too rapidly and the chance of rupture is great.

29. Class Reptilia • 6200 species • amniote • Each of the 3 main groups within the Class Reptilia have marine representatives: • turtles • sea snakes • marine lizards • Each of these groups: • are ectothermic • breathe air using lungs • are covered with scales and an impermeable skin • have salt glands that concentrate and excrete salt • 3.5 chambered heart

30. Marine Turtles • Most successful living marine reptile • 8 Species • More streamlined • Shell lacks enough internal space for head and limbs • Forelimbs are modified as flippers • Hind limbs act as rudders • Most abundant and wide spread are the 2 species of green sea turtles • oviparous

33. The largest of the turtles is the Atlantic Leatherback • Have a skin covering the shell • Reach 2 meters in length • Weigh more than 6oo kilograms (1300 pounds) • All marine turtles are in danger of extinction: • breeding beaches are being developed • Their eggs and shells are in demand • They drown in fishing nets • Feeding areas are polluted • Floating plastic bags are mistaken for food and eaten

35. Marine Crocodiles • One living species • Lives in mangrove swamps and isolated mainland shores in the tropical western Pacific • Very aggressive and hunts in packs • 7 meters long • Weighs over 2.000 pounds • oviparous

36. Marine Lizards • One surviving species – Galapagos Marine Iguana. • Live among the intertidal rocks and beaches of the Galapagos Islands • Grow to more than 1 meter in length • Weigh 9 kilograms (20 pounds) • Swim by undulating body and tail • Live in colonies and feed on off-shore seaweeds. • oviparous

37. Sea Snakes • 50 species of sea snakes • Most are native to the Indian Ocean and the western Pacific areas • There are none in the Atlantic • They hunt among the coral heads • Sea snakes must return to the surface to breathe • The young are born alive in the water • Venom is among the most powerful animal poison known. • Prey is held in the mouth until saliva which contains the neurotoxin enters wounds and takes effect. • Largest is the Yellow Sea Snake (9.8ft)

39. Class Aves • Marine birds: • are endotherms – they generate and regulate metabolic heat • have thin hollow bones without fatty insulation • have light weight beak replacing jaws and teeth • 4 chambered heart to circulate blood under high pressure • have a respiratory system that can accept large quantities of oxygen • 8800 species • Amniotes • Oviparous -all birds lay eggs on land • Only 3% of known birds are classified as sea birds. • Sea birds have salt secreting glands in their head like marine reptiles.

40. Groups of sea birds: • Tubenoses • 100 species – world’s most oceanic birds; examples – albatrosses, petrels and shear waters • Albatross • Wingspan of 12 feet • Weighs 22 pounds • Wings are aerodynamic; can soar at high speeds using very little energy • Pelicans • This group includes pelicans, cormorants, frigate birds, and Boobies • All have throat patches • All have webbed feet • They do not spend much time over open ocean • The frigate can not walk or swim; its skeleton weighs less than its feathers

41. Penguins • Have lost the ability to fly • Excellent swimmers • Have fatty insulation making feathers greasy • Neutrally buoyant; can dive to depths of 875 feet and stay submerged for 10 minutes

42. Class Mammalia • 4500 species • 3 Living groups • Cetacea – Porpoises, dolphins, and whales • Carnivora – seals, sea lions, walruses and sea otters • Sirenia – manatees and dugongs • All exhibit mammalian characteristics: • endothermic • breathe air • 4 chambered heart • give birth to living young • young suckle milk produced in mammary glands • have hair at some time during life • amniote • Oviparous, viviparous, ovoviviparous

43. All marine mammals have 4 common features: • Streamlined body shape with limbs adapted for swimming (drag is reduced by a slippery skin or hair covering) • They generate internal body heat through high metabolic rate and conserve the heat by layers of insulation (fat or fur) • A respiratory system modified to collect and retain large amounts of oxygen. • Many osmotic adaptations allow marine mammals to do away with the need for fresh water.

44. Order Cetacea • 90+ species • Range in size from 6 feet to 110 feet • Can weigh up to 110 tons • viviparous • Suborder Odontoceti (toothed whales) • Have teeth and are active predators • Have a high brain weight to body weight ratio • Use echolocation (biological answer to sonar) to find prey

45. Suborder Mysticeti • Baleen whales – have no teeth; filter feeders • (blue whales, humpback, and grey whales)

46. Order Carnivora • Suborder Pinnipedia (seals, sea lions, and walruses) • True seals – smooth head, no external ears • Elephant seals have diving record of 5,120 feet.

48. Suborder Fissipedia (Sea Otter)

49. Order Sirenia • Bulky, small brained manatees and dugongs • Herbivores 15 feet; 1500 pounds