### animal | echinoderm:

Sea urchin
* Many sea urchins eat algae that grows on rocks on the sea floor
  - have venomous spines
* Most sea urchins are classified as echinoderms
  - dioecious, i.e. the sexes are separate
  - mass spawners, producing several million eggs
  - vegetarians, with a few omnivores thrown in
* Most sea urchins eat algae
  - plants
  - feed on algas
* Most sea urchins have ability
  - behavioral responses
  - globular shapes
  - mouths
  - natural predators
  - other natural predators
  - sensitivity
* Most sea urchins live in areas
  - life
  - warm water
  - possess five pairs of external gills, located around their mouths
* Most sea urchins reach maturity
  - sexual maturity
  - use spines
* Some sea urchins can dig holes into rocks with their teeth
  - die of sickness
* Some sea urchins eat kelp
  - seaweed
  - feed on kelp
  - find on beaches
  - found on coral reefs have especially sharp spines that are dangerous to divers
  - grow throughout life
* Some sea urchins have brains
  - claws
  - cloacas
  - larvae
  - little claws
  - hide in holes
  - produce a toxin during mating season that makes sea urchins dangerous to eat
* are a common sight on rocky shores throughout the world
  - favored prey of the horn shark
  - typical organism that utilizes external fertilization
  - an important part of the marine ecosystem due to their role as scavengers
  - by far the most important grazers in kelp communities
  - echinoderms found in warm and cold saltwater all over the world
  - echinoderms, in the same family as starfish
  - ecologically important and often greatly affect marine communities
  - flat, globe-shaped animals
  - found in oceans all over the world
  - generally herbivorous, feeding on kelp forests
  - grazers and eat seaweed
  - herbivores
  - herbivorous grazers, algae such as kelp is their main diet
  - highly dependent on the number of acetylcholine
  - in the same phylum as A. hermit crabs
  - just starfish with the arms sewn up
  - like vacuum cleaners of the ocean floor
  - major components of marine communities
  - marine creatures
  - more diverse today than they have ever been
  - omnivores that eat plants and animals in their environments
  - omnivorous animals and therefore eat both plant and animal matter
* are one of the favorite foods of sea otters and is also wolf eels
  - more exciting seagrass animals
  - traditional model organisms in developmental biology
  - primarily herbivorous
  - prized around the world for their fishy-flavoured roe and flesh
  - saltwater dwellers, never found in bodies of freshwater
  - sea creatures that live in oceans all over the world
  - sensitive to touch, light, and chemicals
  - small, spiny, marine creatures that look like pin cushions
  - sought out as food by birds, sea stars , cod, lobsters, and foxes
  - spiny-skinned animals
* are the greatest natural enemy of the kelp forest
  - major grazer on kelp, climbing up the holdfasts and chewing through the stipes
  - tiny round spiny creatures that feed on kelp and are related to starfish
  - typically small, rounded, spiny creatures found on shallow rocky marine coastlines
  - used in public aquariums as an indicator organism for water quality
  - very similar to humans up through gastrulation
* brandish their spines on the seafloor near the Channel Islands.
* can also be toxic by ingestion
  - clearcut and devour kelp forests with an average advance of a foot a day
  - reach sexual maturity very quickly and their lifespan is fairly long
  - vary greatly in colour
* crawl slowly on the bottom of the ocean floor, using their spines as stilts.
* eat algas
  - drifting algae or scrape it off rocks
  - mostly plants found on rocks and on the sea bottom
  - the kelp, the otters eat the sea urchins
* emerge from their rocky lairs to feed.
* exhibit a generalized light sensitivity all over the body.
  - organic matter in the seabed
* gather in large groups that contain both males and females.
* graze on kelp.
* have a general sensitivity to light all over the body
  - globular body and long spines that radiate from the body
  - lot of sensory cells, but rather few sensory structures or organs
  - round shaped body and with long spines that come off it
  - adhesive tube feet
  - among the most diverse feeding modes within the Echinodermata
  - ball-shaped bodies covered with long, movable spines
  - claw-like structures on the surface of the body, scattered among the spines
  - five paired rows of tiny tube feet which are found amongst the spines
  - flat or globe shaped bodies and are covered in spines
  - globe-like shape of the body that is covered with large number of long spines
  - long spines that are used for such functions as protection
* have many predators, such as sea stars, octopus, wolf eels, crabs, and sea otters
  - spines connected to their body
  - sharp spines and have known to puncture and damage dry suits
  - strong responses
  - tubular feet called pedicellariae, which enable movement
  - two types of venomous organs - spines and pedicellaria
* inhabit rocks or mud along the seashores.
  - common in sushi
  - the mid to low level of the tide to find the food
  - near the shore, and fragments of their shells are often found on beaches
* move about on their tube feet.
* move slowly, feeding primarily on algae
  - with many species feeding mostly on algae
* occupy places
  - special places
* play an important ecological role as grazers of marine algae.
* possess both a water vascular system and a hemal system, the latter containing blood.
* produce a prodigious number of hardy gametes and can be easily seen with naked eye.
* require special tools necessary to crack the shells and separate and remove the roe.
* take places.
* undergo radial, reductive cleavage.
+ Sea urchin, Ecology: Echinoderms
  * Sea urchins feed mainly on algae, but can also feed on sea cucumbers, and a wide range of invertebrates such as mussels, polychaetes, sponges, brittle stars and crinoids. Baumiller T.K. 2008. Sea urchins are one of the favorite foods of sea otters and is also wolf eels. Left unchecked, urchins may devastate their environment, creating an 'urchin barren', devoid of macroalgae and associated fauna. Sea otters have re-entered British Columbia, dramatically improving coastal ecosystem health by eating sea urchins.