Colorful Corals and Cuttlefish

Well, its been about a week-and-a-half, and I think I have finally caught up to Darwin (the man has a lot of energy and just doesn’t slow down).  I am now at February 3^rd in his journal and will try to continue to post more of less in conjunction with the dates of his entries.

Still in the Cape Verde Islands, Darwin has a short entry today – including:

“Walked along Eastern coast & found some beautiful corals.” (Feb 3)

He frequently refers to corals, and particularly comments on their color and beauty (in one case comparing them to the small, drab corals found in the waters around England). Much like with vegetation, Darwin is excited to be among such a wealth of diversity. Most of the corals he mentions in the Cape Verde Islands are probably shallow or found in tide pools, though in one case he “dredges” for them offshore (unsuccessfully).

Coral species that that are common in the shallow waters of the Cape Verde Islands include Porites astreoides and Siderastrea radians shown below.  It is likely Darwin collected samples of these very species. (Corals shown are from Corelpedia, and picture the same species living in the Caribbean).

For a short scientific paper on the subject see Coral assemblages of Cabo Verde: preliminary assessment and description from 2008.

In Voyage, Darwin describes a Aplysia and cuttlefish that he encounters in his explorations. An Aplysia is a type of sea slug – essentially a relative of the gastropod (snail) without a shell.  Cuttlefish are a type of cephalopod, related to octopus, squid, and nautilus. Scientifically, both are considered a type of mollusk (distant cousins of oysters and clams, too).

Aplaysia species (Aplysia californica from the North Pacific) releasing ink (Wikipedia commons)

As in other observations in Cape Verde he is taken by the variety of colors found in the tropics. I love how he is able, in two paragraphs, to describe these two critters using all of the following “colorful” terms – “dirty yellowish”. “veined with purple”, “purplish-red fluid”, “dark chestnut-brown ink”, “brownish purple”, “yellowish green”, “French grey, with numerous minute spots of bright yellow”, “tint between a hyacinth red and a chestnut brown”, “almost black”, and “various coloured fluids”. Indeed, the cuttlefish was a particular prize to Darwin’s color-sensitive eye, as they had the “chameleon-like power of changing their colour”.

Cuttlefish (from wild-facts.com):

Like all cephalopods, cuttlefish highly developed eyes- much like ours.  A result of what will later (relative to Darwin) be known as convergent evolution.

“Here’s looking at you, squid.” (RJV)