chordate diversity

Question 1

four defining features of chordata?

Answer 1

Notochord
Dorsal, hallow nerve cord-
Pharyngeal slits or clefts-
Muscular, post anal tail

Question 2

Cephalochordata (Lancelets) feeding method

Answer 2

filter feed by a mucous net

Question 3

The 2R Hypothesis

Answer 3

genome duplication events between 564 and 450 MYA

(cephalochordata & tunicates have a single gene while vertebrates have 2 or 4 equivalent)

Question 4

Myxini (hagfish)

Answer 4

Agnathans- “without jaw”
Feed by knotting and using teeth-like processes on tongue
Cartilaginous skeleton
Well developed notochord

Question 5

Petromyzontida (Lampreys)

Answer 5

Agnathans – “without jaws”.
Larvae filter feeders, adults parasitic or do not feed. Notochord and simple vertebral column.

Question 6

how many jawed fish clades are there

Answer 6

4
Chondrichthyes
Placoderms
Acanthodians
Osteichthyes

Question 7

characteristics of Chondrichthyes

Answer 7

cartilaginous skeleton
well developed jaw
no swim bladder
lateral line system

Question 8

fertilisation in Chondrichthyes?

Answer 8

all internal fertilisation

Question 9

Actinopterygii (Fin fish)

Answer 9

Ossified endoskeleton (e.g. bones)
Skin covered in scales and mucus
Swim bladder
teleosts
Fins supported by rays
Jaw modifications

Question 10

fertilisation in Actinopterygii

Answer 10

most have external fertilisation

Question 11

Actinistia (Coelacanths)

Answer 11

fleshy fins
hinged skull
oviparous
2 living species

Question 12

Dipnoi (lungfish) closest living relative to?

Answer 12

tetrapods

Question 13

Osteichthyes

Answer 13

jawed with mineralise skeletons

Question 14

origin of tetrapods

Answer 14

Date from late Devonian (375 MYA)
Limbs evolved from the fins of lobe-finned fish

Question 15

Characteristics of amphibians

Answer 15

Thin skin with limited keratinisation
Skin permeable to oxygen and water
Most restricted to damp environments

Question 16

the amniotic egg

Answer 16

4 specialised membranes
protect from desiccation,
allow gas exchange,
store food and waste

Question 17

origins of amniotes

Answer 17

Carboniferous period

Question 18

two main clades of amniotes

Answer 18

reptilia and mammalia

Question 19

Testudines (turtles)

Answer 19

Terrestrial, freshwater and marine
Shells and skeleton are unique to clade

Question 20

ancient reptilian characters in turtles

Answer 20

Skull morphology.
Scales (b-keratin).
Internal fertilisation but lay eggs
Ectothermic.

Question 21

crocodilia (crocodiles and alligators)

Answer 21

All semi-aquatic predators ;most tropical
Have changed little since the Triassic.
Secondary palate.
Heart with septum, like birds.

Question 22

characteristics of aves (birds)

Answer 22

Feathers (b-keratin).
Large, keeled sternum.
Fore-limbs modified for flight.
Hind-limbs for bipedal walking.
Internal fertilisation and hard-shelled amniotic eggs.
Endothermic.

Question 23

sphenodontia (Tuatara)

Answer 23

One species of lizard-like
Carnivorous reptile found on islands off the coast of New Zealand

Question 24

Squamata (snakes and lizards)

Answer 24

Mainly tropical, terrestrial carnivores

Question 25

specialisation in snakes

Answer 25

limbless
elongated
modified jaw and skull

Question 26

characteristics of mammals

Answer 26

Hair (a-keratin).
Specialised teeth (heterodont).
Articulation of jaw between dentary and squamosal bones.
Endothermic.
Internal fertilisation.
Amniotic eggs.
* Mammary glands.