Echinoderms – and we’re back

echinoderm Echino = spiny Dermis = skin 580 million years old 5 part radial symmetry “tube feet” Internal skeleton (endoskeleton) Water vascular system

A closer look – Form and Function Closely related to humans??? At least amongst inverts 5 part body No anterior No posterior No brain 2 sided – oral (mouth) vs. aboral (“back”)

Form and function continued Internal water vascular system – important Madreporite = Outside sieve Hydraulic pumps Hundreds of movable tube feet Act like vacuums/suction cups “walking”

Feeding Tube feet pry open shells Stomach flip out! Eat animal in its own shell Algae scrapers Filter feeders Detrius feeders

Respiration + Internal transport Thin walled tube feet Diffusion Skin gills No system to carry away CO2 and waste Distribution performed by digestive glands Fluid in body cavity

Excretion Feces = anus Cellulose waste = ammonia Except brittle stars Tube feet and skin Sea cucumber bum ----------------

Response Primitive nervous system Nerve ring around mouth + radial nerves 200 light-sensitive cells Eyespots on arms Statocysts Balance Spines and hiding

Movement Tube feet Movable spines – sea urchins Flexible arms Wings??? Sea Cucumber – like a worm

Reproduction (and regeneration) Male or female Testes or ovaries (in arms!) Detection of gametes Larvae metamorphose Regeneration – must contain part of a middle

Different types Sea stars (“starfish) Brittle Stars Tropical Longer, flexible arms Shed arms & run Sea urchins/Sand dollars Disc shaped Sea Cucumbers Sea lilies/Feather stars

Echinoderms and us… Control population of other marine life Other animals Distribution of algae Delicacies (food) Medicine Anti-cancer/anti-viral Embryology + testing drugs