Deceptive Courtship Signalling in Mourning Cuttlefish

Cuttlefish are a group of marine animals related to squid, octopuses and nautiluses. 'Cuttle' is a reference to their unique internal shell, the cuttlebone; and despite their name, cuttlefish are true mollusks.

Cuttlefish can change color, patterning and their shape to some extent in order to avoid predators or capture prey by blending into their natural surroundings. Male mourning cuttlefish (Sepia plangon) also have specific courtship patterns and color schemes they use in attracting females. When a female is nearby, the male will present to her a stripped courtship pattern on his mantle that indicates sexual interest. Females display a spotted pattern during these encounters. If the female likes what she sees, mating will ensue.

Some cuttlefish males have been observed to display the courtship pattern towards a female while simultaneously displaying a female pattern to a nearby rival male. This deception reduces the probability of aggressive behavior and courtship disruption on the part of the rival male, because he perceives two females, not another male displaying to a receptive female. Male cuttlefish who use deceptive split-signalling are often more successful at mating with females than males who don’t engage in split-signalling, but instead do it the old fashioned way by repelling the advances of other males – a tactic that requires much more energy and poses greater risks for injury.

Cuttlefish males will only use split-signalling under very specific circumstances, namely in the presence of one or more females and a single, lone male on the opposite side of his body, so that the deception works. When split-signalling deceptions are discovered by other males, they typically react with more aggression towards the deceptive male than they do towards rival males not using deceptive signalling. So split-signallers take a risk, but if they are skillful deceivers they are more likely to pass on their genes.

Deceptive Vibratory Communication Helps Protect Pupal Cells of Japanese Rhinoceros Beetles

The Japanese rhinoceros beetle is a group-living beetle that spends the majority of its life (sometimes up to two years) developing underground before emerging from the soil as an adult beetle. Found throughout Asia, it is popular in gambling where bettors wager on the survival of their favorite beetle. Two males are placed together near a female beetle, and sensing a chance to mate with her, they will engage in ferocious battle using their specialized "horns" until only one is left.

The rhinoceros beetle goes through several distinct life stages before reaching adulthood. Eggs are laid in the soil by the adult female just before she dies. The eggs hatch and the worm-like larvae feed on wood and other vegetation in the soil. Next, each larva builds a specialized structure called a pupal cell, in which it will undergo the next life stage as a pupa. The pupal cell is constructed from soft soil, or hummus, vegetation, and faecal pellets. Once finished, the larva is encapsulated in the pupal cell where it becomes a pupa, and then transitions into its adult (beetle) form over the course of several months. The beetle breaks out of the pupal cell and makes its way towards the surface where it will live above ground for a few months before mating and dying.

Because of its group-living social structure, hundreds of rhinoceros beetle larvae can be feeding and burrowing in the soil among already-completed pupal cells. There is a high risk that some larvae may collide with one of these delicate structures and fatally interrupt pupation. In order to deter burrowing larvae, pupae emit strong vibrations that cause a "freeze response" in the larvae, and stops them in their tracks. Researchers believe that pupae have taken advantage of the larvae's response to vibrations, which are most commonly given off by the their natural predator, the mole. Pupae exploit the freeze response by mimicking the vibrations produced by moles, and repel nearby larvae. This is an example of what researchers call "deceptive vibratory communication" and it is used by several other species of group-living insects that make delicate underground pupal cells.