| Pseudamphithoides incurvaria | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Amphipoda |
| Family: | Ampithoidae |
| Genus: | Pseudamphithoides |
| Species: | P. incurvaria |
| Binomial name | |
| Pseudamphithoides incurvaria (Just, 1977)[1] | |
| Synonyms[3] | |
| |
Pseudamphithoides incurvaria is a species ofamphipodcrustacean in the familyAmpithoidae. 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 frompredatory fish.
Two new single-species amphithoid genera were described in close succession in the mid-1970s,Pseudamphithoides Ortiz, 1976[4] andAmphyllodomus Just, 1977. The latter hadA. incurvaria as its type, with thespecific name referring to the moth genusIncurvaria, whose cocoon is built similarly toA. incurvaria's home.[2]
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,[1] they further added: "[we] saw specimens of the genus from Puerto Rico in 1975 and had the same difficulty initially placing the genus in a family."[1]
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 theplumose antennae.[5]
This amphipod is found in the tropical west central Atlantic Ocean, including theCaribbean Sea.[6] Its depth range is from the shallowsubtidal zone down to about 27 m (90 ft).[7]
Aherbivore,P. incurvaria feeds exclusively on the flat-bladed brownalgaDictyota bartayresiana. Thisseaweed contains aditerpene alcohol that is distasteful to fish but not to the amphipod. The amphipod also uses pieces of the alga to build itself a home.[8] 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.[8][9] Researchers found that the amphipods selectedD. bartayresiana to build their domicile even where it was rare, but would not use the seaweedUlva unless there was no alternative. However, treatingUlva with pachydictyol—A, a major secondary metabolite ofD. bartayresiana, made it acceptable. The study concluded that the host specificity of the amphipod was primarily driven by the need to avoid predation.[10]
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.[5]
