Gnathiids are a family of isopod crustaceans whose larvae feed on the blood of fish. During the day, infected parrotfish seek out cleaner fish to consume the parasites; however, at night they are relatively vulnerable to attack. Parrotfish overcome this vulnerability by secreting a mucus cocoon before sleeping which envelopes their bodies with a protective biopolymer that functions similar to a mosquito net. The mucus is secreted from large glands in the gill cavity and is composed of small glycoproteins which are extensively cross-linked through pyrosulfate bonds. This exopolymer net allows small molecules to permeate but prevents the parasitic gnathiids from entering. The process is thought to involve a combination of blocking odorants ...

There's more to studying than simply memorization and practice. It turns out that your diet also plays a pivotal role in recalling key bits of information, while keeping you energized and focused in the process. We're not talking about those scam-ridden supplements that promise a boost in brain power, but simple natural foods such as milk, nuts, seeds, rice, and oats.

The nutrients found in these items help your study efforts by releasing natural memory enhancers called CCKs ( cholecystokinin). When CCK crosses the blood-brain barrier, it acts as a neurotransmitter associated with memory. Studies have shown that learning and memory processes are severely damaged (in rats) that genetically do not respond to the presence of CCK. And in people ...

This is a white-blooded ice fish, or "crocodile fish" (Chaenocephalus aceratus). They lack both red blood cells and hemoglobin, and so have white blood. They have translucent bodies, and absorb oxygen directly from the water around them.

This photo shows a diver almost being eaten by a whale shark, the world's largest fish species. Marine photographer Mauricio Handler captured the intense moment during a dive in Isla Mujeres, Mexico, when more than 600 of the 12-metre-long animals gathered to feed on tuna spawn.

Meet the guineafowl puffer (Arothron meleagris), all puffed-up and poisonous to deter any would-be predators. Found throughout the Indo-Pacific and Eastern Pacific Oceans, this spotty species loves feeding on tiny marine invertebrates and the tips of coral.

This bright blue fish, named the blue parrotfish, can be found in the waters of the Atlantic Ocean, and spends 80% of its time searching for food.

This is the red-eyed gaper, a type of anglerfish that can be found up to 2km below the ocean's surface. Its large head and red blobby face may not look too attractive, but the gaper lures prey in with the shiny patch between its eyes.