LECTURE 17 STUDY GUIDE (ECHINODERMS)

in which phylum are echinoderms classified?

echinodermata

what are echinoderms?

triploblastic bilaterian deuterostomes

what cleavage do echinoderms have?

radial hoboblastic cleavage

what symmetry do echinoderms have?

secondary radial symmetry

what order does the echinodermata form? (mesoderm, ectoderm, endoderm)

1. ectoderm

2. endoderm

3. mesoderm

what does the mesoderm and blastopore turn into?

mesoderm forms at apex of the archenteron

blastopore becomes anus in late stage gastrulae

secondary opening (deuterostome) becomes mouth

what does the growing archenteron turn into in an echinoderm?

extends towards the ectoderm forming a mouth

what is the development of the gut tube in an echinoderm?

continues to elongate the body and established three body axes of a bilaterian in planktonic larvae

what is an echinoderm bipinnaria larvae?

bilaterally symmetrical (bilaterian)

sea star larvae

where do echinoderms live?

ocean/marine

sea stars are echinoderms. what were the other examples that were mentioned that are also echinoderms?

• brittle stars

• sea urchins

• sea cucumbers

• feathered stars

• sea daisies

• sand dollars

discern between the symmetry of a larval and adult sea star

larval sea star —> bilaterally symmetrical; secondary radial symmetry

adult sea star —> radial symmetry

echinoderms have a unique form of locomotion called a water vascular system. what role do tube feet and the madreporite play in this system? where is each located on the sea star?

• sea stars/asteroidea use the water vascular system to move/grab prey with terminal tube feet found in each arm

• tube feet use moving water to move in/out and secretions to adhere/release

• madreporite helps regulate water movement

what do adult sea stars secrete?

calcareous plates often with spines forming a hardened endoskeleton (with superficial epidermis) to protect inside

what are sea star gill filaments do?

penetrate the [] for gas exchange

where are gonads found in sea stars and are they monoecious or dioecious?

found in each arm and they are dioecious

what is sea star wasting disease?

SSWD = arm autonomy followed by a melting-like atrophy/death

what is likely cause of SSWD?

• sea star associated densovirus (SSaDV) a single stranded DNA virus in the parvoviridae

• warmer water

how do sea stars clone themselves?

autonomy/regeneration to clone themselves