Vertibrate Beginnings and Fish

1. Notochord
2. Dorsal, tubular nerve cord
3. Pharyngeal pouches and gill slits
4. Postnatal tail
Deffinition?

Subphylums:
- Urochordata
- Cephalochordata
- Vertibrata

Tunicates or sea squirts
- marine
- sessile as adults
- tunic: tough structure that surrounds animals; made of cellulose
- larvae form has all four chordate characteristics
*invertebrates

Marine lancelets
- slender, laterally compressed, translucent animals
- 5-7 cm long; live in sandy bottoms of coastal waters
- buried in sand with head sticking out
- blood is colorless because of lack of erythrocytes and hemoglobin
*invertebrate
- ex: AMPHIOXUS - adult has all 4 characteristics

Vertebrates
- largest subphylum in Chordata
- have spinal column (backbone) of vertebrae which forms skeletal axis of body and cranium

Superclass Agnatha

- slender eel-like body
- no jaws
- no paired fins or scales
- external fertilization
- cartilage skeleton
- 2-chambered heart
- digestive system without stomach

Hagfish; wrinkle faced slimer, slime balls of sea
- all marine scavengers
- almost blind attracted by keen sense of smell and touch (barbells)
- often ties know and passes it forward for leverage when eating
- produces large amounts of slime
- females produce small number of large, yolky eggs
Sci name?

Lamprey; jawless
- "stone sucking" grasp stone with mouth to hold position
- only parasitic vertebrates in fish
- marine and freshwater
- ammocoetes: small larvae that lasts3-17 years before metamorphing into adults
- attach to sides of fish with rasping teeth( suck like leech; anticoagulant)
- invaded Great Lakes in 1913 and 1918

Cartilaginous fish
- have cartilaginous endoskeleton
- ventral mouth with jaws
- placoid scales: small tooth-like structures
- digestive system with j-shaped stomach
- 2-heart chambers
- resporation by gills
- no swim bladder; squaline: oil that liver produces for buoyancy
- internal fertilization with separate sexes

- body fusiform with hederocerrcal tail caudal fin
- keen sense of smell
- lateral line system: serves as "distance touch" (detects and locates moving animals or objects in water)
- ampullary organs of lorenzini: receptors on sharks head that can detect bioelectric fields
- immune to cancer
- powerful jaws and sharp teeth
Ramora?
Bull?

Carries first atomic bomb to a pacific island, on way back Japanese sub fired two torpedoes and cut it in half, 900 men floating in sea with life jackets, 579 dead, 371 came out alive, 317 lived

1st June 1916: Charles, out with dog 25, bit his leg off, bled to death
6 July: Spring Lake, man 27 killed, bit off his legs, he bled to death, young disabled boy and businessman
3rd Matawan 12 July: bit off left leg 14 yo but lives

Cartilaginous fishes
- dorsoventrally flattened bodies
- enlarged pectoral fins (wings)
- gill openings a dspiracle on dorsal side
- tail is slender and whiplike
- rays have live birth, skates lay eggs
- eat Mollusks, crustaceans, and small fish
Ex?

Cartilaginous; ratfish
- 30 species
- odd mixture of shark like and bony fishlike features
- seldom caught
- grotesque shape
- beautifully colored with pearly irredescense

Bony fish
- largest class of vertebrates
- bony skeleton
- homocercal tail
- paired fins
- akin with mucous glands and dermal scales
- operculum: bony covering over gills
- swim bladder
- 2 heart chambers
- external fertilization with separate sexes

Bony fish
1. Chondrosteans:
2. Neopterygians:

- 7 species: 6 lungfish 1 lobe finned fish
- diphicercal tail
Ex?

- most economical form of locomotion is swimming
- the larger the fish, the faster it can swim(generally) fastest: Marlin, Swordfish, Amberjack
- sharks: large livers contain squaline
- swim bladder: most efficient floatation device in bony fish: absent in bottom dwellers like flounder

Catadromous:
Anadromous:

Oviparous:
Viviparous
Ovoviviparous
Poikilothermic
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