Nemertean

Nemertea is a phylum of invertebrate animals also known as ribbon worms or proboscis worms. The majority of species are marine, but there are also freshwater and terrestrial species. They are most commonly found in polar and temperate regions, but some species inhabit tropical and subtropical environments.

Anatomy and Morphology

Nemerteans are soft-bodied animals that can range in size from a few millimeters to several meters in length. They are characterized by their long, slender, often brightly colored bodies and a unique eversible proboscis used for hunting and defense. The proboscis is housed in a fluid-filled cavity called the rhynchocoel.

Classification

The phylum Nemertea is divided into two main classes: Anopla and Enopla. Anopla includes nemerteans with a straight proboscis, while Enopla includes species with a proboscis armed with stylets.

Ecology and Behavior

Nemerteans are predominantly carnivorous, feeding on other invertebrates. They use their eversible proboscis to capture prey and can produce toxins for defense. Some species are also known to be scavengers or detritivores.

Reproduction and Development

Most nemerteans are dioecious, with separate male and female individuals. Fertilization is usually external, and the larvae undergo a pilidium larval stage before metamorphosing into the adult form.

Research and Medical Importance

Nemerteans are of interest to researchers due to their complex reproductive cycle and their unique proboscis apparatus. Some species produce toxins that have potential medical applications.

See Also

• Anopla
• Enopla
• Invertebrate
• Rhynchocoel