sea spider Colossendeis sp.

The Colossendeis sea spiders are mostly giant bright-red deep-sea species though some Antarctic species live in shallow depths [1]. The Colossendeis sea spiders are the largest sea spiders with some having leg spans as wide as fifty centimeters and trunks of five centimeters or more [1,4]. Antarctic Colossendeis species are identified by several characters that are hard to see in distant photos [2].

This sea spider is walking across the top of a seastar. Sea spiders are also called pycnogonids. Antarctic and subantarctic sea spiders comprise 251 species, representing 21.5% of worldwide species, with 101 species endemic to Antarctica and 60 endemic to subantarctic areas [4].



Adult sea spiders either suck the juices from soft-bodied invertebrates (like this Colossendeis sea spider is doing here with a jellyfish,) or browse on hydroids and bryozoans.

This Colossendeis sea spider is dining on an anemone.

Sea spiders are exclusively marine and mostly bottom dwelling (benthic) [3]. Male sea spiders carry cemented egg clutches gathered from females until hatching and often after hatching in the larval stages [3]. Since sea spider larvae are not planktonic, sea spider dispersal is slow and intermittent leading to the development of many endemic species among shallow- water sea spiders [3].


This might be a photo of egg transfer/fertilization between female and male Colossendeis sea spiders [2].

The male finds a female with eggs, climbs under or over, and extrudes sperm from each of his leg vents (under one of the short joints near the trunk) as she extrudes eggs from similar vents in the same place [2].


Here's a closer view of those two Colossendeis sea spiders above.

In some sea spider genera, the eggs are relatively large and the female pops out only 4-5; in other genera, the eggs are not as wide as the smallest leg segment and the female puts out sometimes more than 100 eggs [2]. Sometimes males collect balls of eggs (they supply the binding cement) from 5-7 different females and walk with them carried under their body [2].

1: Antarctic and Subantarctic Pycnogonida : Nymphonidae, Colossendeidae, Rhynchothoraxidae, Pycnogonidae, Endeididae, and Callipallenidae. CA Child Antarctic Research Series Volume 69, Biology of the Antarctic Seas 24. Washington DC : American Geophysical Union, 1995; 2: C Allan Child, personal communication, 2000; 3: Marine Fauna of New Zealand: Pycnogonida (Sea Spiders). CA Child.. Wellington : National Institute of Water and Atmospheric Research, 1998. NIWA Biodiversity Memoir 109; 4: Polar Biology 24:941-945, 2001

Identification of photos provided by C Allan Child & Franz Krapp. Text ©Peter Brueggeman. Photographs ©Rob Robbins & M Dale Stokes. Photograph may not be used in any form without the express written permission of Rob Robbins & M Dale Stokes.