Phoxichilidium femoratum (Rathke, 1799)
Common name(s): Spiny-thigh sea spider, Sea spider
|Synonyms: Phoxichilidium tubulariae|
|Phoxichilidium femoratum found by Joanna Cowles on an Epiactis ritteri anemone in a sea cave at Cape Flattery. Leg span 1.5 cm. Since no ovigerous legs are present, this must be a female.|
|(Photo by: Dave Cowles, July 2009)|
How to Distinguish from Similar Species: In Anoplodactylus viridintestinalis the lateral projections from the trunk which serve as the bases of the legs are very close together, virtually touching. Its intestine is bright green. Most other long-legged species have pedipalps as well as chelicerae, plus have well-developed ovigerous legs even in females. Phoxicholidium quadradentatum (not mentioned in Kozloff key) has extremely short auxiliary claws that are so small they may not even be seen.
Geographical Range: Dutch Harbor, Alaska to Laguna Beach, CA. Also common in Europe,Canada, and eastern Russia.
Depth Range: Mostly subtidal.
Male pycnogonids carry the eggs, on special anterior ovigerous
legs which are lateral to the chelicerae
present) but anterior to the first pair of walking legs.
In a study of the life history of a related pycnogonid from the North Atlantic, P. tubulariae, Lovely (2005) found that its development was much faster than has been reported for other pycnogonid groups. P. tubuluriae has a fast developmental mode with an encysted protonymphon larva, with a development time of 21 days as compared to months for other pycnogonids. The larvae hatched and quickly infested the hydroid Tubularia larynx, where they lived within the gastrovascular cavity. Later they emerged, destroying the Tubularia polyp. The abundance of P. tubularia adults peaked in late summer as the hydroid host declined.
|Main Page||Alphabetic Index||Systematic Index||Glossary|
Lamb and Hanby, 2005
Ricketts et al., 1985
Lovely, Eric C., 2005. The Life History of Phoxichilidium tubulariae (Pycnogonida: Phoxichilidiidae). Northeastern Naturalist 12:1 pp. 77-92
General Notes and
abundances, unusual behaviors:
This is a view of the underside of the whole animal
|The closeup photos below show the head from above and below. The large chelicerae are readily seen but there are no pedipalps.|
|Dorsal view. The large chelicerae flank the proboscis, which is ventral to them. The rust-colored eye turret is visible behind the chelicerae.||Ventral view. The proboscis is prominent below the chelicerae. No pedipalps are visible.|
In this photo of the tip of the leg of a 3-mm long specimen, the main claw and well-developed auxiliary claw can be seen. Photo by Dave Cowles, July 2014
This individual is 3 mm long from proboscis to abdomen. A photo of the claws on the tip of its foot is above. Photo by Dave Cowles, July 2014