Echinoderms and Sea Cucumbers

• Echinoderms include sea cucumbers, sea stars, sea urchins, brittle stars, and sand dollars.
• "Echinoderm" means "spiny skin" in Greek.
• Most echinoderms are either sessile or slow-moving.
• Echinoderms possess an endoskeleton beneath the skin.
• They have a water-vascular system instead of a heart or blood system.
• The water-vascular system uses water-filled canals for locomotion, food and waste transportation, and breathing.

Sea Cucumbers (Hollothuroidea)

• Worm-like creatures with 5 rows of tube feet.
• Lifespan: 5-10 years.
• Can grow up to 6.5 feet.
• Vary in color.
• Breathe through their anus.
• Found in all oceans at all depths (benthic).
• Common in tropical/warm waters.
• Ingest organic matter from soil sediment.
• Scavenge for algae, small organisms, and waste.
• Use tentacles to pass food into their mouths.
• Capable of both sexual reproduction through spawning and asexual reproduction through fission/budding.
• Considered delicacies in some cultures.
• Use evisceration (expelling guts) as a defense mechanism.
• Important for soil and sediment filtering and cycling.

Sea Stars (Asteroidea)

• Can live up to 35 years and weigh up to 11 lbs.
• Most have 5 arms but can have up to 50.
• Senses: touch, light, temperature, orientation.
• Tube feet facilitate movement and suction.
• Found in all oceans at all depths.
• Common in kelp forests, tide pools, rocky beds, coral shores, seagrass, and reefs.
• Opportunistic feeders and carnivorous.
• Diet includes clams, oysters, and snails.
• Digest prey externally by expelling their stomach through their mouth and using enzymes.
• Often gather in large groups to feed.
• Can reproduce sexually via spawning or asexually via regeneration/fission.
• Examples include crown of thorns, chocolate chip seastar, sunflower star, and doughboy star.
• Can regenerate lost arms.
• Have eye spots at the end of their arms.
• Use arms to communicate and wrestle when competing for territory.
• Predators include sea anemones, starfish, snails, crabs, and fish.
• Defense mechanisms: sharp spines, bitter-tasting toxic chemicals, secreting toxic slime, and shedding arms.

Sea Urchins (Echinoidea)

• Spherical bodies with extendable spines.
• Spines are used for protection, movement, and sensing.
• Tube feet are used for movement, grasping food, and breathing.
• Can live up to 100 or even 200 years.
• The skeleton is called a "test" and loses spines when dead.
• Found in all oceans at all depths (benthic).
• Generally found on rocky substrates.
• Can drill holes in rock for shelter.
• Scavengers and omnivores, feeding on detritus and algae.
• Possess a mouth called "Aristotle's Lantern" with 5 teeth-like structures.
• Reproduce by spawning.
• Some species carry eggs between their spines.
• Predators include sea otters, wolf eels, and triggerfish.
• Spines can regenerate if broken and may contain poison.
• Capable of causing injuries to divers.
• Some animals use spines as defense weapons.
• Gonads are harvested as a delicacy.