Chapter 34: Deuterostomes

What two phyla are deuterostomes?

Echinodermata and Chordata

What symmetry do echinoderm larvae have?

Bilateral symmetry

What symmetry do adult echinoderms have?

Pentaradial symmetry

What does the shift from bilateral to radial symmetry indicate?

Echinoderms evolved from a bilateral ancestor

What defines the oral surface of an echinoderm?

Location of the mouth

Where are echinoderm ossicles located?

Internal, beneath the epidermis

What material are ossicles made of?

Calcium carbonate

What tissue allows echinoderms to stiffen or soften their body?

Mutable collagenous tissue

What is autotomy?

Ability to intentionally shed body parts

Which echinoderms can regenerate body parts?

Starfish and brittle stars

Which echinoderm class can eviscerate its organs?

Sea cucumbers

Do echinoderms have a brain?

No, they have a nerve ring and radial nerves

What system powers echinoderm tube feet?

Water vascular system

What is the entrance to the water vascular system?

Madreporite

What canal does the madreporite connect to?

Stone canal

What does the stone canal connect to?

Ring canal

How many radial canals extend from the ring canal?

Five

What structure controls tube foot extension?

Ampulla

How does the tube foot extend?

Ampulla contracts and pushes water into the tube foot

How does the tube foot retract?

Longitudinal muscles contract

How is tube foot bending achieved?

Unilateral contraction of longitudinal muscles

How do echinoderms respire?

Through tube feet and body surface

What type of circulatory system do echinoderms have?

Open circulatory system

Do echinoderms have excretory organs?

No

How do echinoderms eliminate nitrogenous waste?

By diffusion through tube feet

Do echinoderms have a complete digestive system?

Yes

Are echinoderms gonochoric or hermaphroditic?

Gonochoric

Where does fertilization occur in echinoderms?

Externally

What type of larvae do echinoderms have?

Free-swimming bilateral larvae

Can echinoderms reproduce asexually?

Yes, by splitting in some species

How many extant classes of echinoderms exist?

Five

What class includes sea stars?

Asteroidea

How many arms do most sea stars have?

Five (or multiples of five)

What do sea stars primarily eat?

Bivalves

What class includes sea lilies and feather stars?

Crinoidea

What class includes sea urchins and sand dollars?

Echinoidea

Do sea urchins have arms?

No

What protects sea urchins?

Movable spines

What do most sea urchins feed on?

Algae

What is the fused ossicle skeleton in sea urchins called?

Test

What class includes sea cucumbers?

Holothuroidea

What unique defense do sea cucumbers use?

Evisceration

What class includes brittle stars?

Ophiuroidea

Do brittle stars have ampullae?

No, their tube feet lack ampullae

Do brittle stars have an anus?

No

What four traits define chordates?

Dorsal nerve cord, notochord, pharyngeal slits, post-anal tail

Do all chordates show all four traits at some point?

Yes

What do pharyngeal slits indicate?

Aquatic ancestry

What supports muscle segmentation in chordates?

Somites

What do muscles pull against in chordates?

Internal skeleton

What are the three subphyla of chordates?

Urochordata, Cephalochordata, Vertebrata

What animals belong to Urochordata?

Tunicates (sea squirts)

Do urochordate larvae possess all four chordate traits?

Yes

Do adult tunicates retain these traits?

No, they lose tail, nerve cord, and notochord

How do adult tunicates feed?

Filter feeding

What surrounds the body of adult tunicates?

A cellulose tunic

Are adult tunicates sessile?

Yes

Do tunicates have segmentation?

No

What animals belong to Cephalochordata?

Lancelets

Do lancelets retain their notochord for life?

Yes

Do lancelets have a head?

No

How do lancelets feed?

Filter-feed using cilia-generated currents

What is significant about lancelets?

They may be the closest living relatives to vertebrates

What animals belong to Vertebrata?

Vertebrates (fish, amphibians, reptiles, birds, mammals)

What structure replaces the notochord in vertebrates?

Vertebral column

What protects the vertebrate brain?

Skull or cranium

What are the first vertebrates to evolve?

Primitive fish-like animals

What group evolved from fishes?

Amphibians

What group replaced amphibians as dominant land vertebrates?

Reptiles

What groups arose from reptiles?

Birds and mammals

What is the neural crest?

Group of embryonic cells unique to vertebrates

What does the neural crest form?

Cranial bones, nerves, jaw structures, pigment cells, parts of heart

What type of circulatory system do vertebrates have?

Closed circulatory system

Do vertebrates have kidneys and livers?

Yes

What materials form the vertebrate endoskeleton?

Collagen and calcium phosphate

Why can vertebrates grow very large?

Strong internal skeleton supports large bodies

When did the first vertebrates evolve?

About 545 million years ago (Cambrian)

What evolutionary innovations allowed vertebrates onto land?

Limbs and lungs

What structure allowed vertebrates to fully adapt to land?

Amniotic egg