Posted by: Rob Viens | February 3, 2012

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 3rd 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)

aplaysia

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):

cuttlefish

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)

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Responses

  1. A logistical curiosity; how did Darwin observe the shallow water sea life? Did to remove the organism from the water and observe on the Beagle, or did he actually get into the water and observe the organisms in their natural environment? If so, did he snorkel? I snorkel and it is the best way to observe animals and plants in their natural environment. I wonder if Darwin did the same?

  2. Great image, Al!

    So far he mentions (or suggests) tidepooling, wading and dredging. I looked a little for his methodology but his main writings (looking quickly) seem to be on the larger-scale features of reefs – including the classic “The structure and distribution of coral reefs” from 1842 (http://darwin-online.org.uk/content/frameset?itemID=F271&viewtype=text&pageseq=1). We’ll have to keep an eye out.

  3. The Aplysia looks a lot like a larger species of Nudabrank (spelling) of which there are many varieties her in Puget Sound. Most crawl along the bottom and are very colorful but one that I have seen here is called a “Spanish Dancer” and it swims slowly by flapping appendages on its side that almost look like wings. Those here in the Sound are a luminous purple and lavender and quite beautiful.

  4. […] encounters with unusual creatures (such as the cuttlefish in St. Jago –see Colorful Corals and Cuttlefish) are always enjoyable to read.  His sheer fascination with their newness, his descriptions of […]

  5. […] has a fantastic vocabulary for color (see also Colorful Corals and Cuttlefish). This is a great skill for an observer in a time before photographs – everything had to be […]

  6. […] – Darwin also saw Aplysia in the Cape Verde Islands (see Colorful Corals and Cuttlefish). Share this:TwitterFacebookLike this:LikeBe the first to like this […]

  7. […] about them one day.  By the way, I’m really enjoying The Beagle Project website, which has a great post about the corals and cuttlefish that Darwin describes. My approach to reading Darwin is definitely eclectic and […]


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