---
title: Crustaceans (Crustacea)
scientific_name: Crustacea
common_name: Crustaceans
rank: Subphylum
published: 2024-11-19T18:41:51.573Z
updated: 2026-08-03T20:53:03.457Z
tags: Crustaceans, Crustacea, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/crustaceans
---

# Crustaceans (*Crustacea*)

## Quick facts

- **Rank:** Subphylum
- **Scientific name:** Crustacea
- **Subcategories:** 7

## How to recognise this group

- rigid outer shell
- body often visibly divided into segments
- multiple pairs of jointed legs and antennae

Crustaceans are marine invertebrates characterised by a rigid, chitinous exoskeleton, segmented bodies, and jointed appendages. Most species feature a cephalothorax covered by a carapace, followed by a segmented abdomen. Body forms vary widely, from the robust crabs and lobsters to the laterally flattened amphipods and dorsoventrally compressed isopods. Sizes range from tiny copepods less than 1 mm (0.04 in) to large lobsters exceeding 50 cm (20 in) in length and crabs with similar leg spans.

They inhabit diverse marine environments, including coral reefs, rocky shores, sandy bottoms, and seagrass beds, found from the intertidal zone down to over 100 m (330 ft) depth. Diet varies significantly by species; many are scavengers, some graze on algae, others filter-feed, and certain groups are active predators. Many are cryptic or nocturnal, sheltering in crevices, under rocks, or in burrows during daylight hours and emerging to forage after dark. Growth occurs through ecdysis, the periodic shedding of their rigid exoskeleton.


## Subcategories

- [Barnacles (Cirripedia)](https://redseacreatures.com/taxon/invertebrate/crustaceans/barnacles)
- [Crabs (Brachyura)](https://redseacreatures.com/taxon/invertebrate/crustaceans/crabs)
- [Hermit crabs (Paguroidea)](https://redseacreatures.com/taxon/invertebrate/crustaceans/hermit-crabs)
- [Lobsters (Achelata)](https://redseacreatures.com/taxon/invertebrate/crustaceans/lobsters)
- [Mantis shrimp (Stomatopoda)](https://redseacreatures.com/taxon/invertebrate/crustaceans/mantis-shrimp)
- [Shrimps (Caridea)](https://redseacreatures.com/taxon/invertebrate/crustaceans/shrimps)
- [Squat lobsters (Galatheidae)](https://redseacreatures.com/taxon/invertebrate/crustaceans/squat-lobsters)

---

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