Bythotrephes longimanus
| Bythotrephes longimanus | |
|---|---|
 |
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| The spiny water flea (below), and the fishhook waterflea (above) |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Branchiopoda |
| Order: | Cladocera |
| Family: | Cercopagididae |
| Genus: | Bythotrephes |
| Species: | B. longimanus |
| Binomial name | |
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Bythotrephes longimanus (Leydig, 1860) |
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| Synonyms | |
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Bythotrephes cederstroemi |
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| External identifiers for Bythotrephes longimanus | |
|---|---|
| Encyclopedia of Life | 1041345 |
| ITIS | 684624 |
| NCBI | 77748 |
Bythotrephes cederstroemi
Bythotrephes longimanus (also Bythotrephes cederstroemi), or the spiny water flea, is a planktonic crustacean less than 15 millimetres (0.6 in) long. It is native to fresh waters of Northern Europe and Asia, but has been accidentally introduced and widely distributed in the Great Lakes area of North America since the 1980s.Bythotrephes is typified by a long abdominal spine with several barbs which protect it from predators.
Bythotrephes longimanus is a cladoceran crustacean (water flea) recognizable with its straight tail spine averaging about 70% of its length. Adult individuals have three to four barbs on the spine, while juveniles have only one pair. The females grow to become larger than the males. The animal has one large eye that is usually black or red. It also possesses a pair of swimming antennae and four pairs of legs, of which the first pair is used to catch prey. Mandibles are used for consumption of prey.
The spiny water flea is similar to another introduced cladoceran of the same family, the fishhook waterflea Cercopagis pengoi, which, however, has a more slender spine featuring a prominent loop-like hook at its end (see figure). There is also variation in the shape of the more robust spine of Bythotrephes itself. Specimens arising from sexually produced eggs have a completely straight and relatively shorter spine. In parthenogenetically produced animals, the spine features a kink in the middle (see figure). Previously, the kinked-spined animals were thought to be a separate species – Bythotrephes cederstroemi. After genetic analysis, it is now considered to be a form of B. longimanus, making Bythotrephes a monotypic genus, (one with only a single species).
The spiny water flea preys on smaller planktonic organisms. Its diet consists mostly of zooplankton, including Daphnia and smaller crustaceans. Bythotrephes can consume 10–20 prey organisms a day. It may also eat other small organisms it comes across.
The spiny water flea is native to northern Europe and Asia, and some parts of central Europe. However, the water flea has spread in recent years to many areas throughout Europe, including some ports and inland lakes outside its natural range.
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Wikipedia