Clypeaster oshimensis is a species of sea biscuit, a type of sea urchin, characterized by its flattened, circular body and short spines. It's also known as a sand dollar or cake urchin. Clypeaster oshimensis is a marine invertebrate with a calcareous shell. The shell consists of two valves, and the mantle has two lobes corresponding to the valves. It is found in the Indo-Pacific region.
Here's a more detailed breakdown:
Shape and Size:
Clypeaster oshimensis is known for its flattened, circular body, giving it a sand dollar or cake-like appearance.
Spines:
The surface of the sea biscuit is covered with short spines, which are often described as furlike.
Mouth:
The mouth is located on the underside (oral surface) and is not prominent.
Habitat:
This species is found in marine environments, specifically in the Indo-Pacific region.
Classification:
Clypeaster oshimensis belongs to the family Clypeasteridae, within the order Clypeasteroida. It is also sometimes classified under the subgenus Pavaya.
Tripneustes gratilla, commonly known as the collector urchin or Halloween urchin, is a species of sea urchin. It's a herbivorous echinoderm found in various tropical habitats like coral reefs, seagrass meadows, and algal forests. These urchins have a dark, often bluish-purple test (shell) with white or orange spines, sometimes completely white or orange-tipped.
Key Features and Behaviors:
Color: While typically dark, their spines can vary from white to orange, with some having orange tips or being entirely white.
Test: The test is usually dark, especially in interradial regions, which are the areas between the spines.
Spines: They possess long, obvious spines, and their spines are often inclined towards adjacent ambulacra, giving the appearance of a pentaradiate cross.
Podia: These urchins have long and obvious tube feet (podia) that help them move and collect debris.
Diet: Tripneustes gratilla is herbivorous, feeding primarily on algae.
Habitat: They are found in a variety of tropical habitats, including coral reefs, seagrass meadows, and algal forests.
Covering Behavior: They are known for their "covering behavior," using tube feet to cover their aboral (top) surface with debris like rocks and other materials.
Predators: Common predators include pufferfishes, octopuses, and humans.
Venom: They possess venom but it doesn't typically cause severe stings.
Edibility: While they are not the most commonly consumed sea urchin, some cultures do eat their gonads.
Other names: They are also known as cake, Parson's hat, Halloween, Hawaiian, priest-hut, pincushion, and hairy sea urchins
Diadema setosum, commonly called the diadem urchin or long-spined sea urchin, is a species of long-spined sea urchin known for its distinct five white dots and extremely long, hollow, mildly venomous spines. It's a typical sea urchin, with a round, hard shell (test) and numerous spines. Diadema setosum is primarily found in the Indo-Pacific region, including areas from Australia and Africa to Japan and the Red Sea.
Key Features:
Spines: Long, hollow, and sharp spines that can cause painful stings, though only slightly venomous.
Test: A round, hard shell made of fused plates.
Color: Black or dark brown, with five distinctive white spots on its body.
Habitat: Shallow tropical reefs in the Indo-Pacific, from Australia to Japan and the Red Sea.
Behavior: Primarily a grazer, active at night, and vulnerable to predation from fish.
Size: Maximum test diameter of 90 mm.
Symbiotic relationships: Can host the urchin shrimp Stegopontonia commensalis.
Diet: Algae.
Distinguishing Features:
Diadema setosum can be distinguished from its sister species, D. savignyi, by the presence of white spots on its test, while D. savignyi has blue markings.
Mespilia globulus, commonly known as the Globular Sea Urchin, is a small, spherical sea urchin found in tropical shallow reef habitats. It's characterized by its radially symmetrical, globe-shaped body and relatively small spines, usually brown, red, or dark in color. This sea urchin can grow up to 5 cm in diameter and is known for its algae-eating habits.
Here's a more detailed description:
Size and Shape: The Globular Sea Urchin is small, with a maximum diameter of about 5 cm. Its body is spherical, making it resemble a small, spiny ball.
Spines: It has relatively short spines, which can grow up to 2 cm long. These spines are typically brown, red, or dark in color.
Habitat: Mespilia globulus is found in shallow, tropical reef habitats.
Diet: It is a herbivore, primarily feeding on algae at night.
Behavior: During the day, it often hides on rocks or in crevices, emerging at night to graze on algae. It also exhibits a unique covering behavior, using sponges, shells, and algae.
Appearance: The urchin's radial symmetry and short spines are distinguishing features.
Other Names: It is also known as the Sphere Sea Urchin or the Tuxedo Urchin
