B1 Vertebrates

Question 1

What are fish?

Answer 1

An aquatic chordate, poikilotherm, with fins, scales, gills, appendages.

Question 2

Urochordata

Answer 2

Sea squirts, larval form has a notochord. Not very fish-like.

Question 3

Cephalochordata

Answer 3

Lancelets, smaller group and more fish-like.

Question 4

Craniata

Answer 4

Have cartilage, bone, with a cranium.

Question 5

What is cartilage?

Answer 5

Glycoprotein strengthened by collagen.

Question 6

What is a mineralised skeleton?

Answer 6

External dermal bone, internal and derived from collagen precursors.

Question 7

What does bone do?

Answer 7

Protection and storage of chemicals (phosphates for metabolism).

Question 8

Conodonts

Answer 8

First superclass of fish. Work-like with notochord and v-shaped muscles. Eye capsules, no jaw.

Question 9

Ostracoderms

Answer 9

Dominant in silurian. Bony shields over head and thorax. Dentine-like tissue, eye muscles, inner ear with two semi-circular canals. No jaw. Now split to 4 superclasses.

Question 10

Pteraspiomorphy

Answer 10

Superclass. Genetically small benthic filter feeder. Evolved to have reduced armour and narrower shield.

Question 11

Anaspida

Answer 11

Superclass, small and fusiform. Benthinc, parasitic, detrital feeders. Marine to freshwater, have fins.

Question 12

Thelodonti

Answer 12

Superclass. Small, fusiform, large head and horizontal mouth. Dorsal and anal tails, benthic. Fork-tail form.

Question 13

Osteostracomorphi

Answer 13

Superclass. Large, bony shield with eye, nose and pineal openings. Endoskeleton, epicercal tail and paired fins, complex brain.

Question 14

Myxinomorphi

Answer 14

Superclass (hagfish). Primitive, temperate to cold oceans. No true eyes, burrow in mud, predators of benthic. 70-200 slime glands.

Question 15

Petromyzontomorphi

Answer 15

Superclass (lampreys). 38 living species in one class. Functional eyes, freshwater, might be parasitic. Cerebellum and advanced features. Also an anadromous species (+ freshwater).

Question 16

Lamprey/Hagfish Similarities

Answer 16

Convergent evolution -> tongue, eel-like, jawless, produce pathogen specific defences, no stomach.

Question 17

Hagfish Features

Answer 17

Mucus, continuous fins, terminal mouth, repeat spawning (reproduction), photoreceptors in head, 1-16 gill openings. Bites and tears.

Question 18

Lamprey Features

Answer 18

No mucus, 1-2 dorsal fins, sub-terminal mouth, terminal spawning, sensory organs are pineal organ, eyes and neuromasts. 7 gill openings. Rasping and sucking.

Question 19

How many known living vertebrate species (tetrapoda/fish)

Answer 19

55k. 27k tertrapoda (0.5k marine). 28k fish (16k marine).