pycnogonida

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Scientific photography by Arthur Anker

1.- Crab megalopa (Carpilius sp ?)

2.- Stilapex montrouzieri (Moorea, French Polynesia)

3.- Euthamneus cf rostratus (Moorea, French Polynesia)

4.- Stauromedusa (French Polynesia)

5.- Pilumnus vespertilio (Madagascar)

6.- Notospermus tricuspidatus (Moorea, French Polynesia)

7.- Diopatra sp

8.- Galeommatid bivalve, possibly Scintilla sp

9.- A thalassematid echiuran (Madang, Papua New Guinea)

10.- Male ovigerous sea spider (Pycnogonida)

http://www.flickr.com/photos/artour_a/sets/72157623477677107/

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Stylopallene longicauda

…is a species of callipallenid sea spider (not a true spider, only distantly related) that occurs of the coast of Southeast Australia. Like other sea spiders S. longicauda inhabits relatively shallow waters and is a predator. Like most sea spiders S. longicauda likely feeds on sessile invertebrates like sea anemones and hydroids, sucking out their bodily fluids with its proboscis, which leaves them alive but deflated.

Classification

Animalia-Arthropoda-Chelicerata-Pycnogonida-Pantopoda-Eupantopoda-Nymphonoidea-Callipallenidae-Stylopallene-S. longicauda

Video/Image: Bill Kuiper and Michael McKnight

Yellow Kneed Sea Spider

Despite their appearance, the so called Sea spiders are not actually true spiders, they are marine arthropods belonging to the Class Pycnogonida, but in fact their relationships are enigmatic. They may represent a very early branching of the chelicerate lineage. There are approximately 1000 described species of pycnogonids, all of which are marine.

Pycnogonids vaguely resemble spiders, with small bodies and relatively long, hinged legs. Unique characteristics include an unusual proboscis (mouthparts), which varies in size and shape among species. The body itself is not divisible into neatly- organized tagmata or regions as it is in most other arthropods. An anterior region bears, besides the proboscis, three or four pairs of appendages, including the first pair of walking legs. Some species have more than four pairs of walking legs. 

The photo shows a showy pycnogonid in the Family Callipallenidae. 

Reference: [1]

Photo credit: ©Sylke Rohrlach

Locality: New South Wales, Australia

I was watching that harvestmen video and remembered about existence of sea spiders, which are not spiders though, but what always creeped me out is that their body is of the same width as their legs, and is really small in comparison so when you see them you’re like “So this is the head… and those are legs… and here legs are atteched to the body… WHERE IS THE BODY???”,  and that’s the creepy thing about them.

But then I also remembered that apparently humans look like this:

And that this is actually not much further from sea spiders, and for most of animals we really look noodle-ish. And especially creepy considering that we’re mammals. Naked mammals who walk on two of appendages. Naked omnivorous mammals who only eat meat after ridiculous exposure to forces of destruction that none of the scavengers can beat. 

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"Giant Sea Spider" (Colossendeis colossea)

…a large species of sea spider (not a true spider but distantly related) that has been observed in deep waters worldwide. True to its name C. colossea is the largest species of pycnogonid known to science, with individuals reaching leg spans of around 2 ft! Like other sea spiders this species is a carnivore/scavenger and likely feeds on sessile invertebrates by inserting its proboscis into them and sucking out their insides.

Classification

Animalia-Arthropoda-Chelicerata-Pycnogonida-Pantopoda-Colossendeidae-Colossendeis-C. colossea

Images: Mylène Bourque and Cliff1066

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Stearns’ Sea Spider (Pycnogonum stearnsi)

…a species of Pycnogonid sea spider (not an actual spider) that is native to the western seaboard of North America. Ranging from British Columbia to California and Japan. P. stearnsi are typically found form the mid shore down to the low water mark. They feed mainly on cnidarians like sea anemones and hydroids and occasionally sea squirts as well. They feed by thrusting their proboscis into their prey and sucking out its bodily fluids, leaving it alive but flaccid.

Classification

Animalia-Arthropoda-Chelicerata-Pycnogonida-Pantopoda-Pycnogonidae-Pycnogonum-P. stearnsi

Images: Gary McDonald and Peter J. Bryant

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Pycnogonum littorale

…is a species of Pycnogonid sea spider (not a true spider but distantly related) that is widely distributed from the Arctic to Southern Spain. P. littorale inhabits the littoral and sublittoral zones and like other sea spiders feeds mainly on sessile invertebrates (chiefly cnidarians). They feed by inserting their proboscis into their selected prey and sucking out its bodily fluids, leaving it alive.

Classification

Animalia-Arthropoda-Chelicerata-Pycnogonida-Pycnogonidae-Pycnogonum-P. littorale

Images: Paul Tranter and Tino Soriano