ChordatesLEC32

Question 1

class Ophiuriodea

Answer 1

• brittle stars

- have a distinct central disk & long, flexible arms

Question 2

class Echinoidea

Answer 2

• Sea urchins and sand dollars

- have no arms, but have five rows of tube feet & teeth

Question 3

class Crinoidea

Answer 3

-Sea lilies(sessile) & Feather Stars(free-living)

Question 4

class holothuroidea

Answer 4

• Sea cucumbers
• lack spines, and their endoskeleton is much reduced
• defend by shooting their intestines

Question 5

phylum Chordata

Answer 5

humans

Question 6

all chordates share what characters?

Answer 6

• nerve cord
• Notochord
• muscle segments
• gill slits (develop into parts of neck in terrestrial vertebrates)
• TAIL

Question 7

Marine Tunicates

Answer 7

• Sea Squirts (our closest relative?)
• earliest branch of chordates
• resemble other chordates during their “tadpole” larval stage
• adult tunicate is a filter feeder

Question 8

subphylum Cephalochordata

Answer 8

• Lancelets

- named for their bladelike shape

Question 9

Craniates

Answer 9

-chordates with a skull, cephalization

Question 10

T or F, Cephalization opened up a new way of feeding for chordates

Answer 10

true

Question 11

what is earliest craniate fossils called?

Answer 11

• Haikouella
• 3-cm-long
• Discovered in China in 1999

Question 12

most primitive surviving craniate

Answer 12

hagfish

Question 13

characteristics of hagfish

Answer 13

• jawless with a cartilage skull
• no vertebrae
• defend with slime
• scavengers, feed on dead animals

Question 14

Vertebrates

Answer 14

• craniates with a backbone

- during the Cambrian period some craniates evolved into vertebrates

Question 15

how many species of vertebrates are there?

Answer 15

• 52,000, which include the largest animals ever to live on Earth, whales
• discover new ones all the time

Question 16

Vertebrates’ Derived Characters

Answer 16

–Vertebrae enclosing a spinal cord
–A skull
–Fin rays (in aquatic forms),
–limb bones

Question 17

what is the oldest living group of vertebrates?

Answer 17

-Lampreys that have cartilaginous vertebrae & no jaws

Question 18

Gnathostomes

Answer 18

-vertebrates with jaws, currently out numbers jawless

Question 19

placoderms

Answer 19

earliest Gnathostomes that were extinct armored fish

Question 20

class Chondrichthyes

Answer 20

• have a skeleton made of cartilage
• cartilaginous skeleton evolved secondarily from a mineralized skeleton
  ex. HARMLESS? sharks, sting rays, saw fish