A squid's human-like pregnancy

Gonatus onyx, commonly known as the black-eyed or clawed armhook squid, is abundantly found in the Atlantic and Pacific oceans. Little has been known about its life history because they spawn at great depths, making it difficult for researchers to study them. But with the recent developments in technology and fishery, Seibel and his colleagues (2005) were able to observe its brooding behavior - a very important insight on the reproduction of this species.

Squids are believed to be non-guarders, that is, they deposit their eggs on the sea floor and let them develop on their own. This species, though, begs to differ. It uses its hooks to hold the egg mass (2,000-3,000 eggs), extending from the mouth to well beyond its arms. Because of low temperatures (this happens at X,XXX m depths) and the relatively large size of their eggs, egg development is prolonged. The female squid can, therefore, carry this egg mass for a maximum of 9 months, much like women of our species. And despite of muscle degeneration at sexual maturation, female squids are able to protect their eggs from the inevitable threat imposed by the deep sea. All mothers have this intuition, regardless of what species they are. As Barbara Kingsolver once said, "Sometimes the strength of motherhood is greater than natural laws."

To know more about the black-eyed squid, visit SeaLifeBase.

If you have other information on them, you can e-mail us at sealifebase@fin.ph or come be a collaborator.

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Seibel, B.A., B.H. Robison, and S.H.D. Haddock. 2005. Post-spawning egg care by a squid. Nature (Brief Communications) vol. 438, 15 December 2005 issue, p.929. See article here.


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The Twilight saga continues under the sea

Nowadays we often associate the word “twilight” with “vampires”. Try searching the first word in Google and at the top of the list is The Twilight Saga: Breaking Dawn Part 2. In this context though, we are not going to talk about the epic book  (or movie) but about something that is also related to twilight – coral spawning.

The synchronized mass spawning of corals occurs annually, particularly only at twilight during a full moon. It is characterized by millions of minute particles being released into the water column, floating freely along the current, and forming a slick that extends meters wide and kilometers long and where fertilization takes place [1]. Factors that trigger this event are, viz.: chromatic changes based on the lunar cycle; temperature; and, day length [2]. Overlapping spawning times happen among species of corals. This was first documented in the Great Barrier Reef in 1981. And thus to achieve maximum fertilization success, as the law of nature dictates, different species respond similarly but independently to timing cues set by the factors said above [3]. Their spawning behavior may be analogous to pollination of plants but remember: corals are animals, not plants.

To learn more about the behavior of corals, visit SeaLifeBase.

“If your ship doesn’t come in, swim out to meet it!” – Jonathan Winters

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[1] Thomas, A. 2002. Hard core spawn. ABS Science.

[2] Sweeney, A.M., C.A. Boch, S. Johnsen, and D.E. Morse. 2011. Twilight spectral dynamics and the coral reef invertebrate spawning response. Journal of Experimental Biology 214:770-777.

[3] Guest, J. 2008. How reefs respond to mass coral spawning. Science 320:621-623. 

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