Vertebrates! Fish & Amphibians! Created by: Andrew Alyssa Robin

Chordates All Chordates have: – A notochord – a hollow dorsal nerve cord – Pharyngeal Slits – Post-Anal Tail

Chordata Unlike echinoderms, the class Agnatha: – Hagfish and other chordate have bilateral body symmetry. – Skeletons are NOT made of calcite, but cartilage. – They have evolved from craniates

This is a hagfish. Be scared.

Word of the Day Paedogenesis- the act of reproduction by an organism that has not achieved physical maturity. –

Chondrichthyes: Bony Fishes! Jawed fishies obtained jaws when the two skeletal supporting rods in their gills modified to open and close their mouth This eventually strengthened to form jaws to capture food.

Sharks V. Bony Fish Bony Fish: – Their skeleton is of bone, go figure. – Their upper jaw is attacthed to their skull. – It gets better, they sometimes have this 2 nd set of jaws called a pharyngeal. Don’t ask me. Sharks: – Shark’s skeletons are formed from cartilage, like your ear! – Shark’s have an upper jaw which is NOT attached to their skull.

Chondrichthyes: Sharkies!

To adapt to sea life, a shark has: – Gills To extract the 02 from the H20 – Fins dorsal, caudal, anal, pelvic, and pectoral. The latter two of which are paired. – Tail Provides forward thrust, whereas fins direct water flow.

Buoyancy Sharks use a large liver filled with oil to stay buoyant. Sharks skeletal system is made of cartilage which is half as dense as bone. Whereas, bone fish use gas-filled bladders as their buoyancy system.

Lateral Line System Primary purpose of the LLS – Detection of vibrations cause by other organisms’ movement. – Can be use by ie., a shark to detect a wounded fish.

Shark’s Skin! Layers of Flexible collagenous fibers called dermal denticles. – Acts like an outer skeleton – Reduces drag from water Bony Fishes use bony scales for skin – Layered with mucus to protect from infections and reduce drag.

Amphibian(s)

Amphibia The Bare Facts of Amphibia: – THREE-Chamber heart – Cold Blooded – Derive Heat From Sunlight – Produce Larvae

Amphibia v. Land To deal with the enviroment of land, amphibians developed: – Legs: Not only for swimming, but support them on land. – Gills replaced with lungs – Skin excretes mucus to stay moist.

Breeding For amphibians to breed, they must return to water For those who don’t they need at least need a moist environment This is because the egg is jelly-like, without moisture the egg will dry out.

Amniote Examples

Vertebrata ALL VERTEBRATE HAVE: – A stiff rod running through the length of the animal with a hollow tube of nervous tissue above it and the gastrointestinal tract below. Tetrapods were essentially the first land bound creatures, developing four (tetra) legs (pods).

More Evolution etc. Amniotic eggs are the next step in evolution, where eggs good be laid on land (ie., turtles) The Amniotes are the organisms that breed amniotic eggs. – In Humans, the amniotic sac is layers of a amniotic membrane – The earliest amniotes were lizard like creatures who laid their brood on land and returned to the sea.