Why fish talk: Clownfish communication establishes status in social groups

Clownfish produce sounds to establish and defend their breeding status in social groups, but not to attract mates, according to research by Orphal Colleye and colleagues.

Previous studies showed that clownfish live in unique social groups, where the largest fish develops as a female, the second-largest is male, and the rest of the group remains gender neutral. If the largest fish dies, the rest of the group moves up a rank to replace the female and male.

Small oxygen jump in atmosphere helped enable animals take first breaths

If oxygen was a driver of the early evolution of animals, only a slight bump in oxygen levels facilitated it, according to a multi-institutional research.

The discovery, calls into question the long held theory that a dramatic change in oxygen levels might have been responsible for the appearance of complicated life forms like whales, sharks, and squids evolving from less complicated life forms, such as microorganisms, algae, and sponges.

Reef fish see colors that humans cannot

Researchers have established that reef fish see colours that humans cannot.

A team from Professor Justin Marshall's Sensory Neurobiology Lab ran a series of behavioral experiments with trigger fish, in a bid to decode how they see the world.

Professor Marshall said previous studies had looked into how goldfish saw colour, but this was the first study into how reef fish discriminate colours.

"Coral reefs are the most colourful environments in the world, and it's now become clear that reef fish see colours we can't," Professor Marshall said.

"Some reef fish, such as the anemonefish 'Nemo' and other damselfish can see the UV wavelengths we protect ourselves from.

"Triggerfish, on the other hand, see more or less the same colour range we do but their colour discriminations are different.

Mosquito preference for human versus animal biting has genetic basis

Mosquitoes are more likely to feed on cattle than on humans if they carry a specific chromosomal rearrangement in their genome. This reduces their odds of transmitting the malaria parasite, according to a study.

Rates of malaria transmission depend on whether mosquitoes bite humans or animals, and whether they rest after that meal in an area where they will encounter pesticides.

Bradley Main, a researcher in the Vector Genetics Lab, and his colleagues investigated whether there is a genetic basis to host choice and resting behavior in Anopheles arabiensis.

Birds can sing louder at higher frequencies to make themselves heard over traffic noise

Animals have developed a variety of strategies for dealing with increasing noise pollution in their habitats. It is known, for example, that many urban birds sing at a high pitch to differentiate their song from the low-frequency sound of road traffic. However, as scientists discovered, this is just a useful side effect. The real reason for this behaviour is that songs at a higher pitch are also automatically louder. The birds can make themselves heard far better in city noise by increasing the volume of their song than by raising its frequency according to Science daily.

Despite the numerous unfavourable environmental conditions they encounter there, many wild animals have colonised cities as a new habitat. In cities they must deal with greater numbers of humans and with more light and noise pollution than they encounter in rural settings. However, the urban habitat also offers certain advantages, for example a more abundant supply of food and new breeding options. Many animals have thus adapted surprisingly well to city life.