tiki Ryan Photographic - Pycnogonida - Sea spiders

 

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Chordates

Invertebrates

Class Pycnogonida

There are around 1300 species of sea spider and they are widely distributed in the world's oceans. They range in size from 1mm to 70 cm with the larger species typically living in colder waters.

Unlike true spiders, the pycnogonids have variable numbers of legs. While specific to a particular species within the class there are species with five pairs and even some species with six pairs.

All species share the characteristic of possessing a tiny cephalothorax and abdomen. So, because there is no space in their "body", the gut and reproductive organs extend into the legs.

Most pycnogonids have a piercing proboscis which they use to ingest food from prey such as bryozoans, sponges, cnidarians and even polychaete worms.

While currently considered to be a "chelicerate" an alternative view suggests that they are an ancestor of the current arthropods and have evolved parallel to them - I'm going to stay awake tonight worrying about this ... as always check the internet for further information.

 

Pycnogonid species 1

Pycnogonid Kadavu, Fiji

Pycnogonid Kadavu, Fiji

Pycnogonid Kadavu, vertical Fiji.jpg

Pycnogonid Kadavu, Fiji, vertical

Pycnogonid species 2

Pycnogonid, Fiordland, New Zealand.jpg

Pycnogonid, Fiordland, New Zealand

Invertebrates

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