Paracrangon

Paracrangon is a genus of deep-sea shrimp in the family Crangonidae, found on the Pacific coasts of North America, Asia, and Australia.[1] Morphologically, they are notable for several autapomorphies, most significantly their unique lack of second pereopods, but also for their partially flexible abdomen, which allows them to assume their defensive cataleptic posture.[2][3][4] Species also have long spines covering their carapace.[5][6] They are distinctive among the Crangonid shrimp, and are almost certainly monophyletic.[2] All species except Paracrangon echinata, the type species, are quite rare.[2]

Paracrangon
P. echinada
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Caridea
Family: Crangonidae
Genus: Paracrangon
Dana, 1852
Type species
Paracrangon echinada
Dana, 1852
Species
see text

Appearance

Paracrangon species lack their second pereopods, and, as they are often used for grooming, their absence may explain why they are frequently found covered with detritus, hydroids, and bryozoans. This may help them camouflage themselves in their surroundings.[7] In some species (P. furcata, P. ostlingos), the second pereiopods are completely absent, while in all other species they are represented by small buds.[2] Paracrangon species are slightly compressed laterally, have free eyes, and an elongated rostrum that is relatively slender and sub-erect.[8][2][9] Their carapaces are strongly sculptured, and their bodies are covered with short, curved setae.[2]

The cataleptic posture, also assumed by some other shrimp, is a defensive posture in which the abdomen of the shrimp is flexed upwards at nearly a 45° degree angle, exposing their spines to any predators.[4][3][10]

P. okutanii

Species

Paracrangon comprises the following species:[1][11]

  • P. abei
  • P. areolata
  • P. australis
  • P. echinata
  • P. furcata
  • P. okutanii
  • P. ostlingos

Paracrangon echinata

Paracrangon echinata is also known as the horned or spiked shrimp, and is the most common and widespread species.

P. echinata is usually brownish in colour, with darker spots. It is most closely related to P. abei.[2] It is found in water depths ranging from sublittoral to 1,380 metres (4,530 ft).[6] It was first described from Puget Sound in the Salish sea, but is found along the North American Pacific coast as far north as Alaska but no farther south than La Jolla, California; and, in Asian waters, in the seas of Japan and Okhotsk as well as the strait of Korea.[2][7][8] The pollexes on their first pereiopods are unusually long, and articulate with their palms.[12] The third pair of pereipods is very fine, and serve a sensory function similar to antennae. They are used to detect prey and probe the shrimp's surroundings.[7]

Feeding habits

A 2011 study found that P. echinata is a lie-in-wait predator, feeding on smaller organisms, primarily amphipods (which constitute over 40% of the diet), polychaetes, and other carideans.[7] The shrimp first detects its prey with its thin pair of third pereiopods, then grabs the prey with its first pair.[7]

References
  1. "Paracrangon Dana, 1852". www.gbif.org. Retrieved 2023-02-04.
  2. Komai, Tomoyuki; Kim, Jyung Nyun (2004-12-30). "Shrimps of the crangonid genus Paracrangon Dana (Crustacea: Decapoda: Caridea) from the northwestern Pacific: taxonomic review and description of a new species from Japan". Scientia Marina. 68 (4): 511–536. doi:10.3989/scimar.2004.68n4511. ISSN 1886-8134.
  3. "Paracrangon echinata Dana 1852 - Plazi TreatmentBank". treatment.plazi.org. Retrieved 2023-02-05.
  4. Lamb, Andy; Hanby, Bernard P. (2005). Marine Life of the Pacific Northwest. Canada: Harbour Publishing. p. 287. ISBN 1-55017-361-8.
  5. Academy of Natural Sciences of Philadelphia.; Philadelphia, Academy of Natural Sciences of (1895). Proceedings of the Academy of Natural Sciences of Philadelphia. Vol. 47. Philadelphia: Academy of Natural Sciences of Philadelphia.
  6. Museum Victoria; Victoria, Museum; Victoria, Museum (1999). Memoirs of Museum Victoria. Vol. 57. Melbourne: Museum Victoria.
  7. Jensen, Gregory C. (2011). "Feeding Behavior of the Horned Shrimp, Paracrangon echinata (Caridea: Crangonidae)". Journal of Crustacean Biology. 31 (2): 246–248. doi:10.1651/10-3390.1. S2CID 85280101.
  8. Occasional Papers of the California Academy of Sciences. The Academy. 1900.
  9. Schmitt, Waldo L. (1921). "The Marine Decapod Crustacea of California" (PDF). decapoda.nhm.org. Retrieved 2023-02-06.
  10. "Glossary". inverts.wallawalla.edu. Retrieved 2023-02-06.
  11. "WoRMS - World Register of Marine Species - Paracrangon Dana, 1852". www.marinespecies.org. Retrieved 2023-02-07.
  12. Wood, Louisa E.; De Grave, Sammy (Sep 2015). "Functional morphology of the first pereiopod in crangonoid shrimps (Crustacea, Decapoda, Caridea, Crangonoidea)". Zoomorphology. 134 (3): 469–486. doi:10.1007/s00435-015-0270-y. ISSN 0720-213X. S2CID 253979472.


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