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Sea Urchins

Sea urchins belong to the group of animals called echinoderms which means "spiny skin". 

Characteristics: 
Shell
A sea urchin's shell, or "test" is round and spiny ranging in size from 3 to 10 cm across. Their color varies from black, dull green, brown, blue, and red. 
Tube Feet
Sea urchins have tiny tube feet found on their spines. The feet act as suction cups that help the sea urchin move about slowly, capture food, and hold onto hard bottom. 
Mouth (Aristotle's lantern)
The sea urchin's mouth is found in the middle of the underside of its body. The mouth has five tooth-like plates for feeding.

Feeding habits: 
Sea urchins are omnivores, meaning they eat both plants and animals, however they feed mostly on algae, along with decomposing matter. Their spines are used for protection and trapping food.

Prey: Sea urchins are prey to many predators in their marine environment. Some of their main predators include crabs, large fish, sea otters, and birds. 

Life cycle:
Sea urchins reproduce during the spring. Sea urchin eggs do not hatch for several months. Juvenile sea urchins become large enough to settle down to the ocean floor between ages 2 and 5 years old. 

Species living at the Sotka Lab

Picture
Juvenile urchin species Echinometra lucunter
Echinometra lucunter
(Rock boring urchin)

Characteristics: elongate oval test (shell), long and slender spines thickened at the base.

Habitat: Commonly found in limestone reef rock in shallow marine environments. 
They use their spines and teeth to create shallow depressions or burrows in rock to hide in.

Scientific classification:
Kingdom: Animalia
Phylum: Echinodermata 
Class: Echinoidea 
Order: Camarodonta
Family: Echinometridae
Genus: Echinometra
Species: E. lucunter


Juvenile Echinometra lucunter are used in feeding assays at the Sotka Lab!

Picture
Photo: LH Sweat, Smithsonian Marine Station at Fort Pierce
Arbacia punctulata
(Purple-spined Sea Urchin)

Characteristics: 
  • Long slender spines, often purple to brown in color with white bases
  • Total diameter including spines can reach 100mm

Habitat: shallow waters, under coral rubble, rocky and sandy bottoms

Scientific classification:
Kingdom: Animalia 
Phylum: Echinodermata
Class: Echinoidea 
Order: Arbacioida 
Family: Arbaciidae 
Genus: Arbacia
Species: A. punctulata
Sources:
http://a-z-animals.com/animals/sea-urchin/
http://www.sms.si.edu/irlspec/Echino_lucunt.htm

Patriots Point Naval and Maritime Museum 
40 Patriots Point Rd.
Mt. Pleasant, SC 29464

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