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Tales from Under the Sea
October 13, 2014
by Molly Michelson
Lost your head? Not a problem.
The BBC reported last week about a species ofHydractinia that can regrow its head if decapitated. That’s a neat trick, yes? The teeny invertebrates—related to jellies, corals, and anemones—live on the backs of hermit crabs and “up close resemble a tree, each with a foot, a trunk and a tentacled head used for catching tasty passing detritus,” according to the post. (I think they resemble Beaker from the Muppets quite a bit.)
How do they do it? Scientists from the University of Galway discovered that the creatures keep their embryonic stem cells for life, making any bodily regrowth, including a head, easy-peasy.
Image: Regenerative Medicine Institute, Galway
Cuttlefish response to ship noise
Cuttlefish (Sepia officinalis) can either be masters of disguise or swimming neon signs, depending on their moods. And now, ScienceShot reports, scientists have discovered that the cephalopods also change their colors in response to ship noise. According to the article, this could be “the first evidence that engine noise may stress the animals out.”
The study, published earlier this month in The American Naturalist, describes that cuttlefish change their colors more frequently when played the sounds of ships, which could possibly mess with their ability to hide from predators or attract cuttlefish mates.
Image: dachalan via Flickr
Fish moving poleward
To understand where our seafood will be found in the future, William Cheung and Miranda Jones of the University of British Columbia examined how 802 commercially important species of fish and invertebrates react to warming water temperatures, to other changing ocean properties, and to new habitats opening up at the poles. The researchers then matched the conditions under best- and worst-case IPCC (Intergovernmental Panel on Climate Change) climate change scenarios.
In the worst-case scenario, in which Earth’s oceans warm by three degrees Celsius by 2100, fish could move away from their current habitats and toward the cooler poles (both the Arctic and Antarctic) at a rate of 26 kilometers (16 miles) per decade. Under the best-case scenario, where Earth warms by “only” one degree Celsius, fish would move 15 kilometers (9 miles) every decade. This is consistent with changes in the last few decades, the researchers report this week in the ICES Journal of Marine Science.
“The tropics will be the overall losers,” says Cheung. “This area has a high dependence on fish for food, diet and nutrition. We’ll see a loss of fish populations that are important to the fisheries and communities in these regions.”
“As fish move to cooler waters, this generates new opportunities for fisheries in the Arctic,” says Jones. “On the other hand it means it could disrupt the species that live there now and increase competition for resources.”