World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0004857714
Reproduction Date:

Title: Cumacea  
Author: World Heritage Encyclopedia
Language: English
Subject: Malacostraca, Jennidayus, Meiobenthos, Grenadiers (fish), Crustacea
Collection: Cumacea, Malacostraca, Mississippian First Appearances
Publisher: World Heritage Encyclopedia


Temporal range: Mississippian–Recent
Iphinoe trispinosa
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Superorder: Peracarida
Order: Cumacea
Krøyer, 1846 [1]

8, See taxonomy

Cumacea is an order of small marine crustaceans of the superorder Peracarida, occasionally called hooded shrimp or comma shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans. They live in soft-bottoms such as mud and sand, mostly in the marine environment. There are more than 1,500 of species of cumaceans formally described. The species diversity of Cumacea increases with depth.


  • Anatomy 1
  • Ecology 2
  • Importance 3
  • Reproduction and development 4
  • History of research 5
  • Fossil record 6
  • Taxonomy 7
  • See also 8
  • References 9
  • External links 10


General body plan of a cumacean

Cumaceans have a strongly enlarged cephalothorax with a carapace, a slim abdomen, and a forked tail. The length of most species varies from 1 to 10 millimetres (0.04 to 0.39 in).

The carapace of a typical cumacean is composed of several fused dorsal head parts and the first three somites of the thorax. This carapace encloses the appendages that serve for respiration and feeding. In most species, there are two eyes at the front side of the head shield, often merged into a single dorsal eye lobe. The five posterior somites of the thorax form the pereon. The pleon (abdomen) consists of six cylindrical somites.

The first antenna (antennule) has two flagella, the outer flagellum usually being longer than the inner one. The second antenna is strongly reduced in females, and consists of numerous segments in males.

Cumaceans have six pairs of mouthparts: one pair of mandibles, one pair of maxillules, one pair of maxillae and three pairs of maxillipeds.[2][3]


Cumaceans are mainly marine crustaceans. However, some species can survive in water with a lower salinity, like brackish water (e.g. estuaries). In the Caspian Sea they even reach some rivers that flow into it. A few species live in the intertidal zone.

Most species live only one year or less, and reproduce twice in their lifetime. Deep-sea species have a slower metabolism and presumably live much longer.

Cumaceans feed mainly on predation on foraminiferans and small crustaceans.[4]

Many shallow-water species show a diurnal cycle, with males emerging from the sediment at night and swarming to the surface.[5]


Like Amphipoda, cumaceans are an important food source for many fishes. Therefore, they are an important part of the marine food chain. They can be found on all continents.

Reproduction and development

Cumaceans are a clear example of sexual dimorphism: males and females differ significantly in their appearance. Both sexes have different ornaments (setation, knobs, and ridges) on their carapace. Other differences are the length of the second antenna, the existence of pleopods in males, and the development of a marsupium (brood pouch) in females. There are generally more females than males, and females are also larger than their male counterparts.

Cumaceans are epimorphic, which means that the number of body segments does not change during development. This is a form of incomplete metamorphosis. Females carry the embryos in their marsupium for some time. The larvae leave the marsupium in the manca stage, in which they are almost fully grown and are only missing their last pair of pereiopods.

History of research

The order Cumacea has been known since 1780, when Ivan Ivanovich Lepechin described the species "Oniscus scorpioides" (now Diastylis scorpioides). At the time, many scientists thought that the cumaceans were larval stages of decapods. In 1846, they were recognised as a separate order by Henrik Nikolaj Krøyer. Twenty-five years later, about fifty different species had been described, and currently there are more than 1,500 described species. The German zoologist Carl Wilhelm Erich Zimmer studied the order Cumacea very intensively.

Fossil record

The fossil record of cumaceans is very sparse, but extends back into the Mississippian age.[6] Fossil Cumaceans from the early Jurassic scarcely differ from living forms (Bacescu & Petrescu 1999).[7]


Diversity of forms as shown here in six of the extant families. (a) Bodotriidae, (b) Diastylidae, (c) Leuconidae, (d) Lampropidae, (e) Nannastacidae, (f) Pseudocumatidae

Cumaceans belong to the superorder Peracarida, within the class Malacostraca. The order Cumacea is subdivided into 8 families, 141 genera, and 1,523 species:[8]

One species is also placed incertae sedis in the order.

See also


  1. ^ H. N. Krøyer (1846). "On Cumaceerne Familie". Naturh. Tidsskr. 2 (2): 123–211, plates 1–2. 
  2. ^ N. S. Jones (1976). British Cumaceans. Synopses of the British Fauna No. 7.  
  3. ^ R. Brusca & G. Brusca (2003). Invertebrates (2nd ed.).  
  4. ^ M. Bacescu & I. Petrescu (1999). "Traité de zoologie. Crustacés Peracarides. 10 (3 A). Ordre des Cumacés". Mémoires de l'Institut Océanographique de Monaco 19: 391–428. 
  5. ^ T. Akiyama & M. Yamamoto (2004). (Crustacea: Cumacea: Leuconidae) in Seto Inland Sea of Japan. I. Summer diapause and molt cycle"Nippoleucon hinumensis"Life history of (PDF).  
  6. ^ Frederick R. Schram, Cees H. J. Hof, Royal H. Mapes & Polly Snowdon (2003). "Paleozoic cumaceans (Crustacea, Malacostraca, Peracarida) from North America".  
  7. ^ Sarah Gerken, 'Cumaceans of the World: Cumacean morphology.
  8. ^ Shane T. Ahyong, James K. Lowry, Miguel Alonso, Roger N. Bamber, Geoffrey A. Boxshall, Peter Castro, Sarah Gerken, Gordan S. Karaman, Joseph W. Goy, Diana S. Jones, Kenneth Meland, D. Christopher Rogers & Jörundur Svavarsson (2011). "Subphylum Crustacea Brünnich, 1772" (PDF). In Z.-Q. Zhang. Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness.  

External links

  • Cumacea page
  • Cumacea at
  • Cumaceans of the World
  • Cumacea World Database
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.