1. Green Sea Urchin (Strongylocentrotus droebachiensis): Found in shallow waters along the Atlantic coast of North America, this species is characterized by its spherical shape and long, venomous spines. Green sea urchins are grazers and feed primarily on algae and other marine plants.
2. Red Sea Urchin (Mesocentrotus franciscanus): Indigenous to the Pacific coast of North America, the red sea urchin has a bright red or purple color and dense, short spines. It grazes on kelp and plays an essential role in maintaining kelp forest ecosystems.
3. Pencil Urchin (Eucidaris tribuloides): Pencil urchins are long, cylindrical echinoids found in various oceans. They have slender bodies with numerous delicate, pencil-like spines. These sea urchins are deposit feeders, ingesting sediment to extract organic matter.
4. Slate Pencil Urchin (Heterocentrotus mammillatus): Originating from the Indo-Pacific region, slate pencil urchins are known for their distinctive blue-black color and elongated spines. They are commonly found in rocky habitats, feeding on algae and detritus.
5. Diadema Urchin (Diadema setosum): Diadema urchins are medium-sized sea urchins with long, venomous spines. They are prominent grazers in coral reef ecosystems, shaping the benthic community structure by controlling algal growth.
6. Edible Sea Urchin (Echinus esculentus): Found in the Atlantic Ocean and the Mediterranean Sea, this species is highly valued for its culinary significance. The gonads (roe) of edible sea urchins are considered a delicacy in many cultures.
7. Fire Urchin (Toxopneustes pileolus): Fire urchins are recognizable by their striking red or orange coloration and venomous spines. They are native to the Indo-Pacific region and typically inhabit shallow waters.
These are just a few examples of the vast diversity within the group of sea urchins. Different species have adapted to specific environmental niches, contributing to the complexity and ecological balance of marine ecosystems.