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Mammary Glands Amniotic Egg Limbs Lungs Bony Skeleton Jaws Vertebrae

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Mammary Glands Amniotic Egg Limbs Lungs Bony Skeleton Jaws Vertebrae Mammary Glands Amniotic egg Limbs Lungs Bony Skeleton Jaws Vertebrae Classification Phylum Chordata Subphylum Subphylum Subphylum Urochordata Cephalochordata Vertebrata Tunicates Lancelets Agnathans Fish Sharks tetrapods Chordate Characteristics Subphylum Urochordata= Tunicates 1. Larvae looks like a tiny tadpole 2. Has a nerve cord down its back, similar to the nerve cord found inside the vertebrae of all vertebrates. 3. Cerebral Vesicle is equivalent to a vertebrate's brain. 4. Sensory organs include an eyespot, to detect light 5. Otolith, which helps the animal orient to the pull of gravity. Subphylum Cephalochordata= Lancelets 1. The dorsal nerve cord is supported by a muscularized rod, or notochord. 2. The pharynx is perforated by over 100 pharyngeal slits or "gill slits", which are used to strain food particles out of the water. 3. The musculature of the body is divided up into V-shaped blocks, or myomeres, and there is a post-anal tail. 4. All of these features are shared with vertebrates. 5. On the other hand, cephalochordates lack features found in most or all true vertebrates: the brain is very small and poorly developed, sense organs are also poorly developed, and there are no true vertebrae. Subphylum Vertebrata= Fish, Amphibians, Reptiles, Birds and Mammals 1. Integument with outer epidermis and an inner dermis integument often modified to produce hair, scales, feathers, glands, horn, etc. 2. replacement of notochord by vertebral column more or less complete 3. Bony or cartilaginous endoskeleton consisting of cranium, visceral arches, limb girdles, and 2 pairs of appendages 4. Muscular, perforated pharynx; this structure is the site of gills in fishes but is much reduced in adult land-dwelling forms -Extremely important in embryonic development of all vertebrates 5. General body plan consisting of head, trunk, 2 pairs of appendages, and post anal tail -These structures are highly modified in many vertebrates and sometimes absent Class Agnatha Hagfish and Lamprey • No jaw • No paired fins • No scales • Notocord rather than vertebral column Class Agnatha Hagfish Hagfish characteristics • Strictly marine • No bone • Rasping tongue • Eyes covered by skin • Numerous slime glands in skin, secrete copious amounts of mucus; • Separate sexes, but all individuals have ovitestis • Eggs deposited at sea; direct development VIDEO: Slime on highway Class Agnatha Lamprey Lamprey Characteristics • Oral disc with epidermal denticles and rasping tongue • Active "predatory parasites” • No bone • Well-developed vertebrate eyes • Well-developed Lateral Line system • Uniformly 7 pairs of gills • Cranium cartilaginous, open on top • Eggs deposited in freshwater; freshwater larva; many species have freshwater adult, but most migrate to sea and have marine adult stage (anadromous). Class Chondrichthyes Characteristics Sharks, skates, rays • Posses jaws with teeth, cartilaginous skeleton, paired fins • Scales (denticles) have same origin and composition as teeth • Possesses 5-7 gills • Lateral line • Relatively unchanged for the pass 480 million years Lateral line: - Present in most fish and is used to sense tiny vibrations in the water. - Situated just under the skin on the snout and along either side of the fish’s body. - Canals that are filled with fluid. - Tiny modified hair cells line its walls and are instrumental in sensing vibrations and movement. Evolution of Jaws in fish chondocranium Hyomandibular arch palatoquadrate Meckel’s cartilage agnathostome gnathostome 1st appeared 400 mya Class Chondrichthyes Sharks, skates, rays pores - Sense organs called electroreceptors - Form a network of jelly-filled pores - Detects weak magnetic fields produced by other fish Modern Sharks • Planktivores • Carnivores • Parasites Gill arch from basking shark Cookie cutter shark- suction cup like mouth Ovipary- eggs enclosed in capsule; eggs are laid and hatched outside the mother Ovovipary- give birth to young, eggs develop in uterus Vivipary- give birth to young, placental connection Basic Shark Anatomy Caudal = Like a tail Dorsal = upper or backside Pectoral = from the chest Class Osteichthyes • Posses jaws with teeth • bony skeleton • paired fins • 4 paired gill arches covered by operculum • Intestine- simple, no spiral valve • Swim bladder • Lateral line • Homocercal tail • Scales- cycloid, ctenoid, ganoid Basic Fish Structure Superorder Chondrostei sturgeon paddlefish • ganoid scales (don’t form rings as they grow) • heterocercal tail • persistent notochord; centra absent or cartilage rings • large mouth, long maxilla attached at rear • open spiracle Superorder Holostei gar • L.Permian-Recent, but mostly Juras. & Cretac.; • Abbreviated heterocercal tail, often symmetric caudal fin; • Ganoid or cycloid scales • Single dorsal swim bladder, hydrostatic & respiratory; physostomous; • No open spiracle • Vertebral centra often at least partly ossified, constricting persistent notochord; • More modernized jaws (than Chondrosteans) - maxilla shorter, free at rear; shorter mouth Superorder Holostei bowfin Superorder Teleostei Fish Diversity 680 species of fish in the islands' waters. About 30% of these fish are endemic to the area . Domino damsel Trigger (Humu) White mouthed morey Porcupine Dwarf moray Achilles tang trumpetfish Subclass Crossopterygii Latimeria • Swim bladder modified to lungs • Paired appendages • May have given rise to terrestrial tetrapods • Bony head • Scales and teeth Coelacanth Thought to be extinct 80 million years ago Found in 1938 off the coast of the Comoro Islands Who found it first? 1938 Marjorie Courtenay-Latimer Where was it found? J.L.B. Smith, Rhodes Univ., Grahamstown Coelacanth Anatomy Fins: • 2 dorsals • 2 pelvics • 2 pectorals • 1 anal • 1 caudal Coelacanth Anatomy Unsegmented notochord Rostral organ Intercranial joint Fat filled swim bladder Ovoviviparous Anatomical comparison between Sarcopterygian, amphibian, and reptile. Anatomical Similarities to Sharks: Spiral valve intestine Give birth to live young Long cartilaginous tube instead of backbone Osmoregulatory strategy Anatomical Similarities to Fish: bony head teeth scales Anatomical Similarities to Tetrapods: • fat filled lung • fleshy lobed-fins • circulatory system • inner ear • tooth enamel • intracranial joint- a feature once found in ancient frogs The coelacanth’s phylogenetic classification remains inconclusive Subclass Dipnoi Lungfish Acanthostega 360 mya Foot of Acanthostega had 8 digits Acanthostega • First complete tetrapod with free digits - eight digits on each hand • Retained “fishy” characters: - gills - tail fin - Partial connection between skull and pectoral girdle - Labyrinthodont teeth - Lateral line - Ulna shorter than radius Ichthyostega Transition fossil from fw Crossopterygian to tetrapod.
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