Wednesday, March 9, 2016

Purple invertebrates in the Abyss!

Another week and another bunch of deep-sea Okeanos dives in the French Frigate/Hawaiian Islands region!

One thing I noticed while reviewing the recent dives and those from last year was just how much COLOR you see in the deep-sea.. black, white, ORANGE... and purple!

Purple is of course, the color of kings! In Chinese painting, purple represents the harmony of the universe because it mixes red and blue. There's a whole bunch of meaning which you can find on Wikipedia..

Functional explanations for animals with black, white (such as this Henricia) or transparent/translucent body walls seem to be explained pretty readily by light-related/lack of pigment type explanations.
And even the bright orange colors in species are considered adaptive.. as orange/red does not reach into the depths, rending animals these bright colors effectively black.
It is interesting then, what about those animals that AREN'T any of these colors??

Why are SO MANY deep-sea animals purple?  

I'm not sure if I'm missing some biophysical explanation.. whether this color has some adaptive significance? Or perhaps simply results in some modification of pigments due to some physiological/defensive/efficiency?? 

Purple (or at least a bold blue) seems to be present in several different phyla of animals in the Hawaiian deeps as observed by the Okeanos Explorer ROV..  Note: These are all pretty deep. 1000-4000 m or thereabouts..

How many purple invertebrates are there??

1. There's this big echinothuriid urchin, Tromikosoma As discussed last week, these walk around on the deep-sea floor with spines modified into walking legs.

The shallow water relatives of these urchins are VERY poisonous and brilliantly colorful! As presented here, a few years ago.

Curiously, another purple echinoderm is this feather star (crinoid), Sarametra triserialis (Zenometridae) as ID by Chuck Messing. 

This "slime star", Hymenaster sp. As has been mentioned before, these are big blobby pillow shaped starfish that emit a noxious mucus when annoyed..
Here is a violet/purple euryalid ophiuroid aka a "serpent star"...

But echinoderms aren't the only purple animals down there! 

We've also observed this squat lobster (Crustacea) on several occasions.. Possibly a new species! (I believe they said it was a chirostylid?) 

 Gorgeous and with a very striking color against the otherwise grey and dark deep-sea bottoms! 

In the phylum Cnidaria we have....

There was this dark blue/purple sea anemone! I believe this was a cerianthid? 

AND this handsome soft coral, Clavularia!
and this very interesting purple coral (apparently a "proper" coral, a scleractinian)


Kevin Bylund said...

I used to flyfish with a purple grub, supposedly because purple was the last color visible at depth, at least that was what I was told.

The Monster said...

Maybe it's to confuse predators/prey, who would associate colors from the violet end of the spectrum with ultraviolet from the surface?