''Pseudamphithoides incurvaria'' is a species of

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

in the family

Ampithoidae Ampithoidae is a family of amphipod crustaceans. The family has a worldwide distribution as algal dwellers. They commonly create tube-shaped nests on their host plants or algae which serve as both shelter and food. Young ampithoids develop from ...

. It is native to shallow water in the tropical western Atlantic Ocean where it creates a home for itself from fragments of the algae on which it feeds. This seaweed contains certain chemicals that are distasteful and protect it from

predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

fish.

Taxonomy

Two new single-species amphithoid genera were described in close succession in the mid-1970s, '' Pseudamphithoides'' Ortiz, 1976 and ''Amphyllodomus'' Just, 1977. The latter had ''A. incurvaria'' as its type, with the specific name referring to the moth genus '' Incurvaria'', whose cocoon is built similarly to ''A. incurvaria''s home. Both authors noted that the genera they were describing were unusual and divergent. This was marked enough that when Karaman and Barnard later noted the synonymy of the two genera, they further added: " esaw specimens of the genus from Puerto Rico in 1975 and had the same difficulty initially placing the genus in a family."

Home

''Pseudamphithoides incurvaria'' lives concealed in a tube of its own construction. Two oval pieces of seaweed are bent in half longitudinally and stuck together along the long edges with a secreted glue, leaving slits open at each end. The anterior part of the animal projects at one end. The "domicile" is carried in a vertical position and the amphipod can clamber around among the hydroids and seaweed around it, and can swim while still enclosed in the casing, using strokes made by the plumose antennae.

Distribution

This amphipod is found in the tropical west central Atlantic Ocean, including the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

. Its depth range is from the shallow

subtidal zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

down to about .

Ecology

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

, ''P. incurvaria'' feeds exclusively on the flat-bladed brown

alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mi ...

'' Dictyota bartayresiana''. This

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

contains a

diterpene Diterpenes are a class of chemical compounds composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being ...

alcohol that is distasteful to fish but not to the amphipod. The amphipod also uses pieces of the alga to build itself a home. Fish have been observed spitting out these casings after they have been ingested, but if the amphipod gets dislodged from the casing in the process, it is readily consumed. Researchers found that the amphipods selected ''D. bartayresiana'' to build their domicile even where it was rare, but would not use the seaweed ''

Ulva Ulva (; gd, Ulbha) is a small island in the Inner Hebrides of Scotland, off the west coast of Mull. It is separated from Mull by a narrow strait, and connected to the neighbouring island of Gometra by a bridge. Much of the island is formed from ...

'' unless there was no alternative. However, treating ''Ulva'' with pachydictyol—A, a major secondary metabolite of ''D. bartayresiana'', made it acceptable. The study concluded that the host specificity of the amphipod was primarily driven by the need to avoid predation. Young amphipods develop in a brood pouch and the juveniles remain inside their mother's domicile for a period of time, protected from predators and provided with easy access to their food supply.

References

{{Taxonbar, from=Q14182770 Corophiidea Crustaceans of the Atlantic Ocean Crustaceans described in 1977