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Coral Share UV Secrets

Corals are shielded by an effective, natural sunscreen that prevents them from being burned. Photograph by the Australian Institute of Marine Sciences.

By David E. Boruchowitz

You’re probably aware that many corals are photosynthetic, making use of the plentiful tropical sunshine to produce their own food with the help of resident zooxanthellae (symbiotic algae in the coral’s tissues). To maximize photosynthesis, these corals live in very shallow water where the sunlight can easily penetrate. As anyone who has visited the tropics can attest, that plentiful sunshine comes with a hefty dose of burning UV radiation. Why don’t corals get sunburned? A team of British scientists studying Acropora coral on the Great Barrier Reef believe they’ve found the answer.

It seems that those zooxanthellae also produce substances that protect against harmful UV rays. Not only do the host corals benefit from this natural sunscreen, fish that feed on the corals also share the protection. This leads the scientists to believe that one day we may be able to get our sunscreen in a pill!

For now, however, they are working on using genetic engineering to obtain bacteria-produced analogues of the sunscreen substances to test in a lotion.

Posted September 1st, 2011.

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Red Shrimp Eating Video

Fire red shrimp. Photograph by MP. & C. Piednoir.

By David E. Boruchowitz

Freshwater shrimp are one of the hottest newcomers to the aquarium hobby, and selectively bred red ones are extremely popular. One of the amazing things you can observe in your pet shrimp is the way they feed. Seeming to stare off into the distance, they sample detritus completely by touch and scent, moving their feeding appendages in apparent fast forward, transferring edible finds to their mouthparts at the same pace. Here’s a close-up video that shows the process:

Posted August 31st, 2011.

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A New Living Fossil!

by David E. Boruchowitz

More than 70 years ago, the discovery of a living coelacanth stunned the scientific world. Thought to have gone extinct in the late Cretaceous, the living fish was known only to local fishermen. More recently a second species of coelacanth was identified. Coelacanths, however, were well known from the fossil record, as was their relationship to lobefin fishes and tetrapods (amphibians, reptiles, birds, and mammals).

Yesterday (May 18) scientists announced an astounding coelacanth-like discovery. The animal in question is a marine cave-dwelling eel that is being called a living fossil, although its line is not represented in the known fossil record. Described as Protoanguilla palau, the fish has many primitive features, but this fish also has gill rakers, a trait of bony fishes previously unknown in any fossil or living eel species. DNA analysis confirmed that this species is an eel, in the order Anguilliformes, but it is so different that it has been given a family of its own, Protoanguillidae.

This animal’s characteristics may be more significant than its not being extinct. What I’m saying is that finding an evolutionary line parallel to that of all other fossil and living eel species is incredible, and just finding fossils of this lineage would have been a great boon. Having an extant species is icing on an already very sweet cake.

As just one example, the absence of gill rakers in all other eels, both fossil and living, suggests that they evolved after the split of Anguilliformes from other bony fish lineages. This new eel suggests that ancient proto-eels may have shared this feature with other lineages but that at some point close after the Protoanguillidae split off, they lost them. Whatever turns out to be the case, this fish, dating back to a time when dinosaurs were just starting their reign, has stayed hidden for a very long time!

Eels, especially moray eels, have great appeal to many aquarists. Their morphological, behavioral, and reproductive traits are unusual and intriguing. In fact, the breeding saga of the common eel is nothing short of amazing. All American and European eels, after many years in freshwater habitats on the two continents, journey to the Sargasso Sea, where they spawn and die. The juveniles slowly make their way north, heading either to North America or to Europe, where they reside until they are ready to spawn.

It’s wonderful to have a fascinating new piece to the great puzzle of life that biologists are slowly putting together. There are many online sites you can enjoy if you’d like to read more about this eel try:

Posted August 19th, 2011.

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