Biology

Tiger shark embryos in the uterus
Tiger shark pups in the uterus, lying perpendicular to the mother's body.

New Strategy for Embryo Nourishment Found in the Tiger Shark

Drs. José I Castro, Keiichi Sato, and Ashby B. Bodine, have discovered a new method of embryonic nourishment in sharks. The tiger shark secretes a nutritive liquid which fills the egg sacs where the embryos are growing, permitting higher numbers of offspring to attain a large size. Their paper, entitled "A novel mode of embryonic nutrition in the tiger shark, (Galeocerdo cuvier)," has just been published in the journal Marine Biology Research.

Northern Elephant Seal (Mirounga angustirostris), Piedras Blancas, San Simeon, CA
Northern Elephant Seal (Mirounga angustirostris), Piedras Blancas, San Simeon, CA

Swine flu found in marine mammals

Between 2009 and 2011, the team of scientists from tested nasal swabs from more than 900 marine mammals from 10 different species off the Pacific Coast from Alaska to California.

They detected H1N1 infection in two northern elephant seals and antibodies to the virus in an additional 28 elephant seals, indicating more widespread exposure. None of the infected seal showed any clinical signs of illness

How can physical barriers, such as isolation on a particular island, lead to the formation of new species through the process of natural selection?
How can physical barriers, such as isolation on a particular island, lead to the formation of new species through the process of natural selection?

How do new species of coral form in the ocean?

In a recent publication in the Proceedings of the National Academy of Sciences, or PNAS, Hellberg and his graduate student Carlos Prada investigate how corals specialize to particular environments in the ocean.

It is very well known that physical barriers and reproductive isolation can lead to the formation of new species on land, especially among plants and animals with short generation times such as insects and annual plants.

Electron micrograph of Bacteriophages (vira) in the process of infecting a cell. This is not the virus or bacteriophage in question but a generic photo

A vaccine for corals

White syndrome' is a name given to a number of diseases exhibiting similar symptoms, such as such as white pox, white band and white plague disease. The causes of white syndrome are in many cases unknown. White syndrome has increased in abundance 20-fold in the last five years, with increases on inner, mid-shelf and outer-shelf reefs along the length of the Great Barrier Reef. It also had a major impact on Caribbean reefs. In areas of the Great Barrier Reef surveyed, white syndrome, along with skeletal eroding band, was the most common disease.

Deep sea crabs are sensible to blue and ultraviolet light
Deep sea crabs are sensible to blue and ultraviolet light

Deep sea crabs see in colour

Investigating deep waters off Bahamas, US-based researchers recorded the glow of tiny bioluminescent species using a submersible vehicle.

Descending to sites between 600 and 1000m down, the scientists observed flashes of bioluminescence where plankton collided with boulders and corals.

The team also studied how crustaceans react to this light, and found previously unknown sensitivities to blue and ultra violet wavelengths.

Sharks can raise their scales to create tiny wells across the surface of their skin, just like the dimples on a golf ball
Sharks can raise their scales to create tiny wells across the surface of their skin, just like the dimples on a golf ball

Shark skin adds speed like golf ball

The minute scales, which are just 200 micrometres long, are made from tough enamel, such as that found on teeth, giving the skin a rough texture like sandpaper. Lying flat, they had previously been found to reduce drag as the shark swims. Some reports had also suggested that sharks can bristle their scales, causing them to stand up on end.

Experiments have now revealed that tiny vortices or whirlpools formed within the cavities between the scales.