Please visit our Sponsors

Related FAQs: Pycnogonids (Sea Spiders), Marine Invertebrates

Related Articles: Marine Invertebrates, Live Rock, Live Sand, Sponges (Porifera), Stinging-Celled Animals (Cnidaria), Worm Groups, Mollusks (Snails, Bivalves, Octopus...)Jointed-Legged Animals (Arthropods), Bryozoans/Ectoprocts, Spiny-Skinned Animals (Echinoderms)

/Natural Marine Aquariums

Sea Spiders, the Pycnogonida

Bob Fenner

Endeis flaccida

    These are tiny (some barely perceptible to the naked eye... a few millimeters to centimeters across) jointed legged creatures that resemble terrestrial spiders (none marine), but have only 4-6 pairs of legs. If you can look close, you'll see they have two pairs of eyes on a rounded knob process that extends from their heads, and a long proboscis.

    Women's libbers will like these animals... though the sexes are separate, it is often the males that carry the fertilized eggs and young about (no planktonic larval stages).

    Most of the 1,200 or so described species are found in association with encrusting invertebrates... all live on the bottom, crawling about. Found worldwide (350 or so species in the Indo-Pacific). in tropical to subtropical seas.

More Commonly Encountered Pycnogonids:

Endeis flaccida Calman 1923. Almost cosmopolitan, both sides of the Central American isthmus, Aden, India, Indonesia... Thick legs, purple dots on them indicative. Usually found on, near hydroids. N. Sulawesi pic.

Nymphon sp. Long, smooth legs with chelipeds, cream to light brown colored consistently. N. Sulawesi. Tiny...

Pycnogonid sp.  Here on Halimeda and the sand bottom in N. Sulawesi.


 These animals aren't necessarily rare in the wild, but are cryptic, small... and easily overlooked. Their presence in captivity is a matter of "luck" in dealing with very fresh live rock... They just "appear out of nowhere" for those fortunate enough... and do no harm to captive marine livestock.

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: