Question

The rhynchocoel is a ________.

circulatory system
fluid-filled cavity
primitive excretory system
proboscis

Answer 1

The rhynchocoel is a fluid-filled cavity in nemerteans that contains the proboscis used for capturing food.

Step-by-step explanation:

The rhynchocoel is a fluid-filled cavity characteristic of the phylum Nemertea, which includes ribbon-shaped creatures known as nemerteans. This cavity houses the proboscis, a specialized organ used by these animals for capturing food. The proboscis can be extended via hydrostatic pressure created by the contraction of muscles surrounding the rhynchocoel. The rhynchocoel houses a specialized proboscis that serves as a harpoon or tentacle for food capture. It can be extended and retracted by muscles in the rhynchocoel wall.

Not to be confused with their circulatory system or excretory system, the rhynchocoel is independent and serves a specific function related to predation.

Answer 2

fluid-filled cavity

Step-by-step explanation:

Rhynchocoel is a fluid-filled tubular cavity present in the organisms of the phylum Nemertea. This cavity lies above the intestines of these organisms in the lower body.

Nemertea is a phylum composed of worms that can be found in shallow water.

These worms have already been classified as a branch of the Flatworms (such as Planarians), with which they are often confused. But recent embryological and molecular evidence points to a phylogenetic relationship with mollusks and annelids. They remind the Flatworms to be non-segmented flat worms. But unlike these, they have a complete bowel with mouth and anus, and a closed vascular system. The article on Planarians can be accessed here.