Sipunculus

Sipunculus is a genus of marine worms belonging to the family Sipunculidae, commonly known as peanut worms. These burrowing invertebrates are characterized by their elongated, cylindrical bodies, which often resemble a peanut when contracted. They are found in various marine environments worldwide, including coastal sediments, reefs, and deep-sea trenches.

Characteristics

Sipunculus species typically range in size from a few centimeters to over 20 centimeters in length. They possess a retractable, muscular proboscis that is used for feeding and burrowing. The body wall is covered with a thin, leathery cuticle, and the body cavity is filled with a coelomic fluid that serves as a hydrostatic skeleton, providing support and facilitating movement.

These worms are deposit feeders, ingesting sediment and extracting organic matter. They possess a unique feeding mechanism involving the proboscis. When feeding, the proboscis is extended into the sediment and used to collect food particles. The food is then transported to the mouth located at the base of the proboscis.

Environments

Sipunculus worms are highly adaptable and inhabit a variety of marine environments. They can be found in both shallow and deep water, from intertidal zones to the abyssal plain. Common habitats include:

  • Sandy beaches and mudflats
  • Rocky shores and reefs
  • Seagrass meadows
  • Mangrove swamps
  • Deep-sea trenches

Reproduction

Sipunculus species are dioecious, meaning they have separate sexes. Fertilization occurs externally, and the larvae are planktonic. After a period of development, the larvae settle to the bottom and transform into juvenile worms.

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