--- title: "Calanus Copepod (Calanus finmarchicus) | AnimalTracks.wiki" description: "A small North Atlantic copepod whose oil sac fuels a winter sleep in deep water." image: "https://animaltracks.wiki/images/animals/calanus-copepod-1.webp" published: "2026-10-11" updated: "2026-10-11" --- # Calanus Copepod (*Calanus finmarchicus*) > **Status**: Checked against 6 sources, listed under Sources below. > **Tagline**: A small North Atlantic copepod whose oil sac fuels a winter sleep in deep water. > **Soundtrack Vibe**: Glacial Ambient & Drone Soundscapes // Steve Roach, "Structures from Silence" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/3v6UGvx3CJ0F0iEq5jWwl1) > **Vibe Match**: Towards the end of summer it descends to deeper water and spends the winter dormant, living off its oil sac. Structures from Silence moves the same way: slow synth tones that hold and barely change from start to finish. ## Biological Superpowers & Stats - **Taxonomy**: *Calanus finmarchicus* - **Danger Level**: Low - **Conservation Status**: Not Evaluated ([IUCN Red List](https://www.iucnredlist.org/)) - **Superpower**: Stores energy in a large oil sac of wax esters - **Habitat**: Cold waters of the North Atlantic, including the North Sea and Norwegian Sea - **Diet**: Algae and other microplankton, including ciliates and dinoflagellates - **Tags**: crustacean, invertebrate, ocean, pelagic ## Natural History & Behavior ## A swimming oil tank Calanus finmarchicus is a copepod, a small crustacean in the zooplankton, the animals that drift with ocean currents. A year-round study in a Svalbard fjord counted one as adult when its prosome, the front part of the body, measured 2.4 to 2.95 millimetres. Its energy store is a large oil sac made of wax esters, built up while it is young and food is plentiful. In one analysis, lipids (fats and oils) made up 22 to 25 percent of the dry weight of its later juvenile stages and adults. It eats algae, but in the open Gulf of St. Lawrence, microplankton that feed on other organisms, including ciliates and dinoflagellates presumed to feed that way, made up a disproportionate share of its ration. ## Sleeping through winter Towards the end of summer, it descends to deeper water and spends the winter dormant, a state called diapause. In that Svalbard fjord, C. finmarchicus overwintered mainly at stage CV, the last juvenile stage, with 65 percent of them there. In the northernmost part of its range, its life cycle takes one year. For copepods, lipid mass is directly related to how deep they can descend during diapause. Smaller reserves mean overwintering at shallower depths, where they are more prone to predation. > **The lipid pump** > In the North Atlantic, this one species sequesters an amount of carbon equivalent to the sinking flux of detrital material, which is debris drifting down from above. ## Food for fish and whales Its lipid stores make it nutritionally valuable to fish and whales. It is widely distributed in the northern hemisphere and is the dominant mesozooplankton species in the North Sea and Norwegian Sea. Atlantic currents regularly carry it in high numbers into the Arctic. It is expanding northwards, and it may potentially replace its larger relative Calanus glacialis if the climate continues to warm. ## Plastic in the pantry In a lab test, juvenile copepods exposed to nylon granules built up less lipid, and those exposed to nylon microplastics moulted, or shed their outer skeleton, earlier than unexposed ones. In a separate feeding experiment, all stages of C. finmarchicus ingested polystyrene fragments, and late juveniles (stage CV) and adults preferred aged microbeads over pristine ones. ## Frequently Asked Questions ### How long does a Calanus copepod's life cycle last? About a year, in the northernmost part of its range. Where researchers sampled it through the winter in Isfjorden, Svalbard, most overwintering animals (65 percent) were at stage CV, a pattern they read as a mainly one-year life cycle. *(Source: [Hatlebakk et al. 2022]())* ### How does a copepod help store carbon in the deep ocean? Overwintering zooplankton carry carbon-rich lipids down and metabolise them at depth. Researchers called this the lipid pump, and found that adding it almost doubles earlier estimates of biological carbon storage in the deep North Atlantic. *(Source: [Jónasdóttir et al. 2015]())* ### Do these copepods eat plastic? In a feeding experiment, yes: every life stage swallowed polystyrene fragments. Much of the plastic passed out again within 2 to 4 hours, and an 11-day exposure did not affect the survival of adult females. *(Source: [Vroom et al. 2017]())* ## Sources 1. [Hatlebakk et al. (2022). Contrasting Life Traits of Sympatric Calanus glacialis and C. finmarchicus in a Warming Arctic Revealed by a Year-Round Study in Isfjorden, Svalbard. Frontiers in Marine Science.]() 2. [Jónasdóttir et al. (2015). Seasonal copepod lipid pump promotes carbon sequestration in the deep North Atlantic. Proceedings of the National Academy of Sciences.]() 3. [Cole et al. (2019). Effects of Nylon Microplastic on Feeding, Lipid Accumulation, and Moulting in a Coldwater Copepod. Environmental Science & Technology.]() 4. [Evjemo, Reitan & Olsen (2003). Copepods as live food organisms in the larval rearing of halibut larvae (Hippoglossus hippoglossus L.) with special emphasis on the nutritional value. Aquaculture.]() 5. [Ohman & Runge (1994). Sustained fecundity when phytoplankton resources are in short supply: Omnivory by Calanus finmarchicus in the Gulf of St. Lawrence. Limnology and Oceanography.]() 6. [Vroom et al. (2017). Aging of microplastics promotes their ingestion by marine zooplankton. Environmental Pollution.]() *Published October 11, 2026. 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