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The sea spider Cilunculus battenae
The sea spider Cilunculus battenae.
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New sea spider found in Norwegian waters

The sea spider Cilunculus battenae was recently recorded in the Norwegian Economic Zone (NEZ) for the first time, when bottom samples from the MAREANO cruises from 2007-2009 were analysed. So far 21 different species have been found in the samples. Two species have previously been observed in the NEZ a few times.

Cilunculus battenae was found at 388 m depth off northern Norway. It has previously been observed further south, at the Wyville-Thompson ridge (between the Faroe Islands and Shetland) and at the Cape Verde slope (West Africa), from  690 - 1160 m depth. The discovery in the NEZ is the northernmost observation of the species. It was first described as late as 1993, possibly because it is a small species easy to overlook.

- We know relatively little about sea spiders, particularly species from the deep oceans. We are therefore focusing on studying the species composition and the geographic distribution of sea spiders found in the MAREANO material,  Arne Hassel,  researcher at The Institute of Marine Research, and Halldis Ringvold,  Marine Biologist at Akvaplan-Niva as, explain.

Sea spiders

There is some disagreement as to how sea spiders should be classified, but for a long time they have been considered arthropods in the class Pycnogonida. They have relatively long legs and small bodies. Unlike spiders that live on land, some of the sea spiders internal organs (such as the digestive tract and reproductive organs) are placed in the legs. Sea spiders are marine animals found in all oceans, and at both poles. Pycnogonida means “with many knees”, and refers to the many leg segments. Sea spiders have four pairs of legs for walking, and their leg span and body length vary greatly. A medium-sized sea spider may have a leg span of 5-7 cm, and large species, can have leg spans of up to 70 cm. The leg span of the largest species found in Norway can reach 25 cm.

Further investigations

- In collaboration with a British expert on sea spiders we have now finished identifying species found, the scientists explain.

They are now going to relate the distribution of sea spiders to environmental conditions such as temperature, depth and sediment.
- We also aim to use nature types in order to describe the pycnogonid habitat preferences, the two scientists explain. 

More photos of sea spiders:

More about sea spiders.

Facts about Sea spiders

Latin name: Pycnogonida (Class)
Size of species from the north-east Atlantic: Total body length, proboscis included: 2 mm-50 mm. Leg span up to about 25 cm.
Life span: Not known
Habitat: Found in all oceans
Food: Mostly carnivorous, feeding on cnidarians, bryozoans, sponges, molluscs and polychaetes.
Characteristic features: Marine arthropods with 4 pairs of legs, proboscis, chelifores, palps, and ovigerous legs

Sea spiders