Echinothrix

Echinothrix is a genus of sea urchins in the family Diadematidae. These urchins are characterized by their long, sharp spines, which can be venomous in some species. Echinothrix species are found in the Indo-Pacific region, inhabiting a variety of habitats, including coral reefs, rocky shores, and seagrass meadows.

Banded Sea Urchin, Double Spined Urchin – Echinothrix calamaris

Common Names

Echinothrix species are commonly known as "pencil urchins" due to the resemblance of their spines to pencils. Some species are also referred to as "fire urchins" because of the venomous nature of their spines.

Characteristics

Echinothrix urchins are easily identifiable by their long, slender, and often brightly colored spines. These spines are typically covered in small, sharp barbs that can readily penetrate skin. The spines are connected to a central test, or shell, which is covered in smaller spines and pedicellariae. Pedicellariae are small, claw-like structures that help the urchin defend itself from predators and clean its test.

The body of an Echinothrix urchin is divided into five radial sections, each containing a row of spines. The mouth is located on the underside of the urchin, surrounded by five jaws. The anus is located on the top of the urchin, opposite the mouth.

Environments

Echinothrix species are primarily found in tropical and subtropical waters of the Indo-Pacific region. They are often found in coral reefs, rocky shores, and seagrass meadows. Echinothrix urchins are herbivores, feeding on algae and detritus. They play an important role in the marine ecosystem by grazing on algae and controlling their growth.

Species

The genus Echinothrix includes several species, including:

  • Echinothrix calamaris
  • Echinothrix diadema
  • Echinothrix echinothrix
  • Echinothrix hardwickii
  • Echinothrix oligospina
  • Echinothrix turcarum

References

For more information on Echinothrix, please refer to the following resources: