Off to a good start.

A friend went diving today and told me she saw a Sea Spider, after getting the info I went back with her and she pointed it out to me, within a minute or two I found two more, all very close to each other and all on the same type of fire coral. I took many photos of them and then I noticed that all three had only six legs each? however the book shows eight and of course spiders have eight legs, very interesting why and how they all had six legs instead of eight..

Nice shot, the sea spiders are not true spiders, they are marine arthropods on the order Pycnogonida (spiders are in the order Araneae). While spiders always have 4 pairs of legs, sea spiders have between 4 and 6 pairs, but that still doesn't solve our problem. Do you have pictures taken closer to the body? It is common to find sea spiders missing legs.

By the way, they feed on corals! That's probably what the one in your photo is doing...

Hi Kriptap,

There is a Wiki on sea spiders and that includes the following paragraph:

In total, Pycnogonids have four to six legs for walking as well as other appendages which often resemble legs. A cephalothorax and much smaller abdomen make up the extremely reduced body of the Pycnogonid, which has up to two pairs of dorsally located simple eyes on its non-calcareous exoskeleton, though sometimes the eyes can be missing, especially among species living in the deep oceans. The abdomen does not have any appendages, and in most species it is reduced and almost vestigial. The organs of this fascinating chelicerate extend throughout many appendages because its body is too small to accommodate all of them alone.

However, I get the impression this means 4 to 6 pairs of legs, and you seem to be talking about 3 pair.

The evolutionary relationship between sea spiders and real spiders (arachnids) is apparently also a very distant one with controversy in the literature. For some of the (hind) legs there is even debate about whether they are legs or leg-like food gathering appendages (see Journal of Zoological Systematics & Evolutionary Research

Volume 43 Issue 1 Page 8 - February 2005).

The real solution to your observation may be the blue-green sea spider leg eater hind. A rarely observed member of the grouper family that exclusive eats the hind legs of sea spiders. They always leave six legs attached so the spider survives and regenerates the legs, ready for the next dinner feast. Check out if you see one on your next dive. It's easy to recognize because it has a blue-green color, but be aware that it is easily confused with the green-blue hind

Bart