For the little bobtail squid, a cloudless night spells trouble. This is because for a predator on the sea-floor, a squid in open water risks casting a shadow against the moonlight. To avoid this, these squid invite a particular type of bacterium to live on the underside of their bodies. As the bacteria respire, they emit a faint blue light, which effectively makes the squid invisible amid the moonlight! 

Honeybees communicate the location of flowers to one another by dancing! This dance, known as the ‘waggle dance’, tells other bees that are watching two important things. Firstly, the direction of the dance tells bees the direction in which to leave the hive to find the flowers, relative to the position of the sun in the sky. Secondly, the duration of the dance tells bees how far they must fly in that direction to find the flowers. Today, researchers watch these dances to learn which areas bees visit to find food, with the goal of conserving these areas.

The Panamanian golden frog lacks middle ear structures which makes them rather hard of hearing. Nevertheless, they still do call to one another. However, to make themselves more obvious, they also wave their front legs at each other!

All of the above have been suggested as possible explanations for this strange behaviour. Perhaps the most controversial hypothesis is the last one. Here, the signal is a ‘handicap’ – producing the signal (i.e. jumping up and down) wastes time and energy. The logic is that only a deer or gazelle that was extremely physically fit could afford to do this. If a weak or old animal jumped up and down rather than fleeing, it would almost certainly not have the energy and stamina left to escape the predator. Thus, the signal is ‘honest’ – if a predator sees a deer or gazelle jumping up and down it knows it must be in excellent shape and is not worth chasing after. 

Male satin bowerbirds have an amazing knack for copying the songs of other birds (this ability is also seen in some parrots and most famously, mockingbirds). But why? In the case of satin bowerbirds, researchers have shown that, for females, the most attractive males are those that can mimic the largest number of other species and do so most accurately. One theory to explain this is that a male’s ability to mimic others tells her something important about his learning abilities.

Elephantfish (and a couple of other species of fish) are ‘weakly electric’ – they’re able to generate weak electric fields using a special ‘electric organ’. The fish can then sense distortions in this field, which indicate the presence of mates, as well as predators and prey. This ability is crucial for fish living in very dark, murky water that prevents visual communication. (N.B. This is different from the famous electric eels of the Amazon, which are able to generate huge voltages that can stun or even kill prey.)

On Kauai, female crickets aren’t the only animals listening out for singing males. A tiny fly, Ormia ochracea, uses the songs to locate male crickets in the dark. When it finds a male, the fly lays a tiny maggot on the male cricket. The maggot digs into the cricket and as it develops it slowly eats it from the inside before finally bursting out as an adult.  Occasionally, mutant crickets are born with deformed, shrivelled wings. These are incapable of singing and would normally be out-competed by singing males. When fly numbers are very high, however, the situation is reversed: singing males are attacked, but mutant males, which are silent, survive.

For its seductive effects on females, this potent protein has been named darcin after Jane Austen’s smouldering hero, Mr. Darcy! If a female gets a good sniff of the urine of a particular male, this protein gets up her nose, making her find the general scent of the urine more attractive AND strengthening her memory of the place that she first encountered it. This means that she is more likely to come back to that specific spot and meet the male himself, who she will then find attractive and want to mate with.

Crayfish ‘talk’ to each other a lot using urine! They’re not alone in doing this – many fish and mammals also send signals to each other in urine. When two crayfish fight, both release large amounts of urine into the water. But why? Experiments have shown that when crayfish are prevented from urinating, fights tend to last longer. This suggests that there’s something in the urine that tells the two opponents who is likely to win. Without this information, fights drag on until one individual is injured and has to give up.

As a result of fishing and tourism, there has been a dramatic increase in boat traffic in areas of ocean inhabited by killer whales. Like many other marine mammals, killer whales communicate with one another using sound. Increased noise from boats has meant that it’s harder for killer whales to hear each other’s calls. There is some evidence, however, that killer whales can overcome this problem to an extent. In the presence of boats, killer whales living off the coast of Washington State have been found to produce longer and louder calls in order to be heard over the din.