---
title: Molluscs (Mollusca)
scientific_name: Mollusca
common_name: Molluscs
rank: Phylum
published: 2024-11-19T18:41:51.573Z
updated: 2026-08-03T21:05:39.575Z
tags: Molluscs, Mollusca, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/molluscs
---

# Molluscs (*Mollusca*)

## Quick facts

- **Rank:** Phylum
- **Scientific name:** Mollusca
- **Body shape:** Invertebrate - Not a fish - coral, mollusc, crustacean, echinoderm and other invertebrate groups.
- **Subcategories:** 9

## How to recognise this group

- unsegmented body, often appearing soft
- many carry an external shell of one or two pieces
- broad muscular foot used to crawl, burrow or cling
- movement slow, or none at all where the animal is fixed in place

Molluscs are invertebrates with soft, unsegmented bodies, typically protected by an external calcareous shell. Some species, however, have an internal shell or lack one entirely. They exhibit a wide size range, from shells a few millimetres long to giant clams reaching 40 cm (16 in) across and squids over a metre in length. Often possessing a muscular foot for locomotion, they are commonly observed on Red Sea reefs.

These animals inhabit diverse environments, from intertidal zones to deep reef slopes, living on or within sand, mud, rubble, seagrass beds, and coral structures. Their feeding strategies vary widely, including grazing on algae, preying on other invertebrates, and filter-feeding plankton. Many species are nocturnal or cryptic, seeking shelter during the day and emerging at night to feed. Cephalopods, such as octopuses and cuttlefish, are particularly notable for their sophisticated camouflage and rapid colour changes.


## Subcategories

- [Cephalopods (Cephalopoda)](https://redseacreatures.com/taxon/invertebrate/molluscs/cephalopods)
- [Chitons (Polyplacophora)](https://redseacreatures.com/taxon/invertebrate/molluscs/chitons)
- [Clams (Bivalvia)](https://redseacreatures.com/taxon/invertebrate/molluscs/clams)
- [Cowries (Cypraeidae)](https://redseacreatures.com/taxon/invertebrate/molluscs/cowries)
- [Nudibranch (Nudibranchia)](https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch)
- [Opisthobranchia (Opisthobranchia)](https://redseacreatures.com/taxon/invertebrate/molluscs/opisthobranchia)
- [Oysters (Ostreida)](https://redseacreatures.com/taxon/invertebrate/molluscs/oysters)
- [Prosobranchia (Prosobranchia)](https://redseacreatures.com/taxon/invertebrate/molluscs/prosobranchia)
- [Sap-sucking slugs (Sacoglossa)](https://redseacreatures.com/taxon/invertebrate/molluscs/sap-sucking-slugs)

---

*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/molluscs)*
*Updated: August 3, 2026*