Class Aplacophora [Mollusca]

By: Prof. Dr. Fazal Rehman Shamil | Last updated: February 3, 2024

Class Aplacophora:

Class Aplacophora have following key characteristics:

Habitat:

Aplacophorans are exclusively marine organisms and are found in various marine habitats, including deep-sea environments, seafloor sediments, and intertidal zones.

Deposit Feeders:

Many Aplacophorans are deposit feeders, consuming organic particles from sediments or detritus.

Radula:

Most Aplacophorans possess a radula which is used to scrape food particles from surfaces or capture prey.

Body Shape:

Aplacophorans have an elongated and vermiform (worm-like) body shape without a distinct head or shell.

Absence of Shell:

Aplacophorans lack a shell entirely. Instead, their body is covered with a thin cuticle that provides protection.

Foot:

They possess a muscular foot that is adapted for burrowing or creeping along the seabed.

Soft-Bodied:

Aplacophorans lack the hard external structures seen in many other mollusks. Their bodies are soft and often translucent.

Gas exchange:

Aplacophorans lack gills for respiration. Gas exchange occurs through the general body surface.

Presence of Rhabdites:

Aplacophorans have specialized cells called rhabdites that produce a mucus-like substance used for locomotion and protection.

Examples of class Aplacophora:

  1. Chaetoderma nitidulum
  2. Epimenia babai
  3. Prochaetoderma yongei
  4. Wirenia argentea
  5. Neomenia grisea
  6. Limifossor pseudobrauneri
  7. Prochaetoderma mariae
  8. Neomenia carinata
  9. Wirenia filiformis

List of Mollusca classes with examples 

Phylum Mollusca is classified into seven major classes namely: