The gender of a baby green sea turtle is determined by the temperature the egg experiences during incubation. When temperatures are warmer, more females are born while. Conversely, when temperatures are cooler, more are males born.

This means that if climate change causes temperatures to rise, sea turtles risk having populations that are composed of nearly all females. If this happens, they may experience a reduction in genetic diversity since few males will be available with which to breed.

Scientists from the University of Exeter, University of Lefke (Turkey) and North Cyprus Society for Protection of Turtles have been studying green sea turtles in Northern Cyprus to assess how diverse the population is and to estimate the impact rising temperatures have had on the turtles thus far.

The research team conducted genetic tests and found that, counter to what they had expected, the green sea turtle population was surprisingly diverse. The data enabled them to estimate how many males were mating with nesting females in the population and they found that there was an average of 1.4 males for every female. Satellite tracking data revealed that males swim vast distances, sometimes thousands of miles during a single breading season. This means that males could be mating between populations that were previously thought to be more genetically isolated.

The study offers hope for sea turtles in the face of the uncertainties posed by climate change. Although rising temperatures remain a threat to sea turtles, there is cause for optimism that green sea turtles can cope with fluctations in temperature better than expected.

Photo © Kimberley Stokes / University of Exeter.

Crustaceans are one of four basic groups of arthropods (the other three being the myripods, arachnids and insects). The group includes crabs, lobsters, shrimp, krill, crayfishes, wood lice and barnacles.

Crustaceans are by no means as diverse in species number as the insects or even the arachnids, but they do come in a mind-boggling array of shapes and sizes. Since crustaceans are with few exceptions aquatic species, they have escaped the demands of life on land (demands which place limitations on the ornateness of body form that can develop).

Crustaceans are an old group of animals, dating back some 500 million years to the Cambrian. Their body plan is simple yet elegant and adaptable. In his book, The Variety of Life, Colin Tudge likens crustaceans to mobile Swiss Army knives—composed of up to 32 segments each equipped with its own pair of appendages that are modified for a variety of tasks: locomotion, defense, communication, feeding, hunting, reproduction. Each segment and its appendage is like a separate tool and together the segments and appendages form as well-adapted a tool kit as a Swiss Army knife.

Photo © Ben Cranke / Getty Images.

Although scientists don't know exactly how many species of arachnids there are alive today, their best guess puts the species count in the ballpark of 100,000 of which, more than 40,000 are spiders. Since that means nearly half of all archnids are spiders, it's easy to forget the other lesser-known eight-legged creatures that belong to the group.

Arachnids include about a dozen subgroups, many of which are obscure groups that most people have never heard of. But there are a few that stand out. The most well-known group is of course, the spiders. But odds are you've probably also heard of a few other arachnid groups. They include: harvestmen, ticks and mites, and scorpions.

Scorpions are easy to recognize thanks to their segmented tails that curl up to a venomous point. Ticks and mites are generaly very small, measuring just a few millimeters in length. Harvestmen are perhaps the group that is most commonly mistaken for spiders. There are about 6,300 species of harvestmen (also known as daddy-long-legs). Members of this group have very long legs and their abdomen and cephalothorax are almost completely fused.

So next time you see something with eight legs, don't immediately assume it's a spider.

Photo © Steve Taylor / Getty Images.