''Calanus helgolandicus'' is a

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

found in the Atlantic, from the North Sea south to the western coast of Africa. The female has an average size of about and the male has an average size of about .

Description

The female has an average size of about and the male has an average size of about .

Distribution

''Calanus helgolandicus'' is found in the Atlantic, from the North Sea south to the western coast of Africa. It can also be found in the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on th ...

and

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, ...

. Because of increasing temperatures due to

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

, its range is expanding northward. It is usually found in waters between in temperature, with maximum abundance being between .

Ecology

Life cycle and reproduction

''Calanus helgolandicus'' overwinters as a stage V copepodite. However, only those with enough energy stores can overwinter; the rest stay at the surface. In fact, it has been observed that overwintering copepods are heavier than those that stay at the surface. During this overwintering process, the copepodites moult into adult females. After moulting, the females breed the next spring. In the absence of food during this time, they can lay their first few eggs from accumulated energy stores. Although this is true, it is mainly an

income breeder Capital breeding and income breeding refer to the methods by which some organisms perform time breeding and use resources to finance their breeding. The former "describes the situation in which reproduction is financed using stored capital; hereas ...

, reproducing using recently gained energy. It has a maximum of about three generations per year. In the central North Sea, it is most abundant during spring and autumn. It is likely that warmer temperatures can facilitate egg production for more of the year.

Feeding

''Calanus helgolandicus'' is a planktonic herbivore, although it has been shown to eat both dead diatoms and faeces from other members of its species. This copepod seems to select particles based on their structure;

marine snow In the deep ocean, marine snow (also known as "ocean dandruff") is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to ...

(which is unstructured), is rejected, whereas dead diatoms and objects such as

polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is ...

(when given as beads 30

micrometer Micrometer can mean: * Micrometer (device), used for accurate measurements by means of a calibrated screw * American spelling of micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; ...

s in diameter) are accepted as food. Faecal pellets are generally not accepted in whole (possibly due to the difficulty in handling very large particles). When faecal pellets are rejected, they are generally damaged. When the pellets are fragmented (corporhexy), they are generally ingested with alternate food, and the "loosening" (coprochaly) of a pellet can precede the removal (and likely ingestion) of the

peritrophic membrane The peritrophic matrix (from the prefix ''peri-'', meaning around, and ''-trophic'', referring to nutrition(food)) or peritrophic membrane is a semi-permeable, non-cellular structure which surrounds the food bolus in an organism's midgut. Although ...

, which has bacteria and other organisms which increase its nutritional value. Its grazing (the efficiency of the removal of food from seawater) and ingestion rates (the actual amount of food eaten) increase with increasing body weight, however, as body weight increases, the grazing and ingestion rates per unit of body weight decrease.

References

{{Taxonbar, from=Q6551932 Calanoida Crustaceans of the Atlantic Ocean Crustaceans described in 1863