Axiidea

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Axiidea
Axius serratus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
(unranked): Reptantia
Infraorder: Axiidea
de Saint Laurent, 1979[1]
Families

Axiidea is an

infraorder of decapod crustaceans. They are colloquially known as mud shrimp, ghost shrimp, or burrowing shrimp;[2] however, these decapods are only distantly related to true shrimp. Axiidea and Gebiidea are divergent infraoders of the former infraorder Thalassinidea. These infraorders have converged ecologically and morphologically as burrowing forms.[2] Based on molecular evidence as of 2009, it is now widely believed that these two infraorders represent two distinct lineages separate from one another. Since this is a recent change, much of the literature and research surrounding these infraorders still refers to the Axiidea and Gebiidea in combination as "thalassinidean" for the sake of clarity and reference.[2] This division based on molecular evidence is consistent with the groupings proposed by Robert Gurney in 1938 based on larval developmental stages.[3]

Axiidea are noted for the burrows with complex architecture that they make in the ocean floor sediment.

biogeochemical processes of the ocean floor sediments, and in the creation of habitats that favor various marine benthic communities.[5]

Classification

The

crabs). The cladogram below shows Axiidea as more basal than Gebiidea within the larger order Decapoda, from analysis by Wolfe et al., 2019.[6]

Decapoda

Dendrobranchiata (prawns)

Pleocyemata

Stenopodidea (boxer shrimp)

Procarididea

Caridea (true shrimp)

Reptantia

Achelata (spiny lobsters, slipper lobsters)

Polychelida (benthic crustaceans)

Astacidea (lobsters, crayfish)

Axiidea (mud shrimp, ghost shrimp, or burrowing shrimp)

Gebiidea (mud lobsters and mud shrimp)

Anomura (hermit crabs and others)

Brachyura (crabs)

(crawling/walking decapods)

The infraorder Axiidea comprises the following families:

A few

disputed ] Similarly, molecular studies do not support the subfamily Eiconaxiidae being separate from family Axiidae.[2] There is also no molecular evidence to separate the subfamily Calocardidae from Axiidae.[2]

The cladogram below shows Axiidea's internal family relationships from analysis by Wolfe et al., 2019.[6]

Description

Axiopsis pica, a species under the Axiidae.[13]

The length of an adult Axiidea can range from about 1.5 cm (0.6 in) in some species, to over 35 cm (14 in) in other species.[14] The color of the Axiidea can range a variety of colors, including white, pink, red, orange, and dark brown. The rostrum can range from being nearly invisible, to fairly rigid and extending past the eyes.[5] The carapace also ranges from fairly rigid to transparent, showing the organs underneath. Axiidea can range from having a well-calcified exoskeleton, to barely calcified elongated exoskeletons, which show an adaptation to burrowing in certain species.[14]

The sex of the Axiidea can be determined by the pleopod structure on the underbelly of the organism. This structure is underdeveloped or absent in the males.[5] The sex ratio in most species of Axiidea tends to be 1:1, although in certain habitats one sex can slightly outnumber the other.[5]

Duration of egg incubation periods, and therefore also larval development, is dependent on the environmental factors surrounding the habitat of each individual species. Environmental factors tend to include developmental constraints, salinity of the marine environment, and temperature of the water.

megalopa stage represents the transition from plankton to their benthic habitats, and morphological development is marked by the growth of functional mouthparts resembling those of juveniles or adults.[3]

Burrows

Burrows can be divided into two groups in terms of external characteristics, depending on the existence of a mound of sediment around the entrance of the burrow. These two groups can be further divided based on whether they contain plant material within the burrow. Burrows tend to be narrow, and can range from Y or U shaped in certain species, to intricate branching tunnels and deep wells in other species.[5]

Burrows can also differ within the classifications of external characteristics, based on the feeding mode for each organism. There are three general

detritophages, or deposit feeders.[5] The other two trophic groups are the drift catchers, which collect plant matter that drifts based on ocean currents, and the suspension feeders, which feed on plant matter that is suspended in the water.[5]

Drift catcher burrows tend to lack the external characteristic of the mound around the entrance of the burrow, and their burrows tend to be very deep and contain chambers that are filled with seagrasses and other sea debris.[5] Suspension feeder burrows tend to be in the Y or U shapes, and also lack seagrasses and debris within them in contrast to the drift catchers; furthermore, the sediment within the lower parts of these burrows can also serve as food for the suspension feeders.[5] The feeding mode affects the burrow, because Axiidea consume amounts of sediment, and the sediment that is rejected makes up parts of the burrow. The seagrasses consumed by the Axiidea are therefore present in the burrows and provide a way to classify the species.[5] The burrows created by detritophage species of Axiidea are more likely to change over the life of the organism than the burrows of filter feeders because detritophage species of Axiidea can build new passages and chambers over the course of their feeding.[5]

Each burrow is typically inhabited by one organism, however, certain species of Axiidea live in pairs.[5]

Distribution and ecology

Axiidea typically live in marine environments with soft-bottom sediments. Axiidea are found in most oceans and seas, except for high latitude polar seas. Distribution shows a clear gradient based on latitude, with low species numbers at higher latitudes and higher species numbers in low latitudes.[14] Therefore, Axiidea are most diverse in temperate to tropical regions. Within the intertidal regions, Axiidea can be used as fishing bait or even for human consumption.[14] Axiidea rarely range into the deep sea with depths more than 2,000 m (6,600 ft), instead with 95% of species preferring the shallow water of intertidal or subtidal (less than 200 m or 660 ft) areas.[14]

References

  1. ^ de Saint Laurent, M. (1979). Vers une nouvelle classification des Crustacés Décapodes Reptantia. Bulletin de l'Office Nationale de Pêche de Tunisie, 3, 15–31.
  2. ^ .
  3. ^ a b c d Pohle, G. and Santana, W., Gebiidea and Axiidea (=Thalassinidea), in Atlas of Crustacean Larvae, Baltimore: Johns Hopkins Univ. Press, 2014, pp. 263–271.
  4. ^
  5. ^ .
  6. ^ Huxley, T. H. (1879). On the classification and the distribution of the crayfishes. Proceedings of the Scientific Meetings of the Zoological Society of London, 1878(3), 752–788.
  7. ^ Dana, J. D. (1852). Conspectus Crustaceorum, &c. Conspectus of the Crustacea of the Exploring Expedition under Capt. C. Wilkes, U. S. N. Proceedings of the Academy of Natural Sciences of Philadelphia, 6, 10–28.
  8. ^ Kossmann, R. (1880). Malacostraca Anomura. In Reise in die Küstengebiete dea Rothen Meeres, Erste Hälfte. Leipzig: Zweite Hälfte.
  9. ^ Sakai K. (1992). The families Callianideidae and Thalassinidae, with the description of two new subfamilies, one new genus, and two new species (Decapoda, Thalassinidea). Naturalists, Tokushima Biological Laboratory, Women's University, 4, 1–33.
  10. ^ Poore, G. C. B. (1994). A phylogeny of the families of Thalassinidea (Crustacea: Decapoda) with keys to families and genera. Memoirs of the Museum of Victoria, 54, 79–120.
  11. ^ "Axiopsis pica Kensley, 2003". WoRMS. World Register of Marine Species. 2018. Retrieved 6 May 2018.
  12. ^ a b c d e Dworschak, P.C. “Methods Collecting Axiidea and Gebiidea (Decapoda): a Review.” Annalen Des Naturhistorischen Museums in Wien. Serie B Für Botanik Und Zoologie, vol. 117, 2015, pp. 5–21. JSTOR, JSTOR, www.jstor.org/stable/43922304