Synidothea bicuspida

Copepod means “oar footed”.  They often referred to as the “insects of the sea”, because of their sheer numbers and similar role in water column and sea-bottom food webs as insects have on land.  They can be found all the way from the surface to the bottom of the oceans, although most species have a specific range of depth over which they are found. A majority of free-living species are benthic and within the order Harpacticoida. Benthic species are the major food item for many other inverebrates, fish, and some shore-birds. After nematodes, harpacticoids are the second most abundant group in the interstitial sediments where they are part of the meiofauna.

Copepods swim or crawl by using the 4 or 5 pairs of legs on their body along with the movement of their mouth parts.  For rapid movement they will also use their tail.  Many copepods are generalist algal/detritous feeders simply “filtering” the food (detritous, plants, and single-celled animals) out of the fluids around them, while some lightly scrap surfaces.  Unlike other copepods, harpacticoids have very short first antennae to facilate ther movement in sediments. Other species are predators or scavengers.  There are also many parasitic forms that will not be considered here.

Like insects, copepods grow by casting off their old exoskeletons, going through a variety of stages (generally 12) after hatching.  Like caterpillars, they have two major life forms, starting out as a nauplius, and then metamorphizing mid-life to the copepodite body form that is shown in most images.  The adults of many species are longer lived, with most harpacticoids carrying their eggs until they hatch.  The nauplius can be as small as 0.05 mm in length, while adults typically range from 0.3 to several millimeters in total length.  We know little for sure about how long most species live in the Arctic, but most probbaly have one or more generations per year.

The order Harpacticoida comprises ~3,000 species worldwide, with at least 206 benthis species known to occur in the Arctic.

Page Author: Russ Hopcroft & Bodil Bluhm
Created: September 20, 2010

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