Mantis Nest

Lore & Background

Stomatopods branched off from other members of the class Malacostraca around 400 million years ago, with more than 520 extant species of mantis shrimp known. All living species are in the suborder Unipeltata, which arose around 250 million years ago. Dubbed "sea locusts" by ancient Assyrians, "prawn killers" in Australia, and now sometimes referred to as "thumb splitters" due to their ability to inflict painful wounds if handled incautiously, mantis shrimp possess powerful raptorial appendages that are used to attack and kill prey either by spearing, stunning, or dismembering.

In Their Own Story

The mantis shrimp's second pair of thoracic appendages is adapted for powerful close-range combat. In Odontodactylus scyllarus, these weapons are employed with blinding quickness, with an acceleration of 10,400 g (102,000 m/s2 or 335,000 ft/s2) and speeds of 23 m/s (83 km/h; 51 mph) from a standing start. Because they strike so rapidly, they generate vapor-filled bubbles in the water between the appendage and the striking surface—known as cavitation bubbles. The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newtons that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow. Even if the initial strike misses the prey, the resulting shock wave can be enough to stun or kill. The species Gonodactylus smithii has the fastest strikes reported for any species of mantis shrimp species, with a speed of 30.6 m/s (110 km/h; 68 mph) and an acceleration of 1.5×105 m/s2.

Reader's Guide

Mantis shrimp typically grow to around 10 cm (3.9 in) in length, while a few species such as the zebra mantis shrimp can reach up to 38 cm (15 in). A mantis shrimp's carapace covers only the rear part of the head and the first four segments of the thorax. The appendage differences divide mantis shrimp into two main types: those that hunt by impaling their prey with spear-like structures and those that smash prey with a powerful blow from a heavily mineralised club-like appendage. Spearers are armed with spiny appendages - the spines having barbed tips - used to stab and snag prey. Smashers possess a much more developed club and a more rudimentary spear; the club is used to bludgeon and smash their prey apart. Smashers use this ability to attack crabs, snails, rock oysters, and other molluscs, their blunt clubs enabling them to crack the shells of their prey into pieces. Spearers, however, prefer the meat of softer animals, such as fish and cephalopods, which their barbed claws can more easily slice and snag.

Did You Know?

• Mantis shrimp have between 12 and 16 types of photoreceptor cells, compared with the four types that humans possess in their eyes.
• The species Gonodactylus smithii has the fastest strikes reported for any species of mantis shrimp, with a speed of 30.6 m/s (110 km/h; 68 mph) and an acceleration of 1.5×105 m/s2.
• Mantis shrimp can perceive wavelengths of light ranging from deep ultraviolet (300 nm) to far-red (720 nm) and polarised light.
• The power amplifier spring mechanism has the limitation that the strike cannot be controlled or directed whilst it is being executed, meaning the trajectory must be prepared either before or after it is delivered.
• Stomatopods branched off from other members of the class Malacostraca around 400 million years ago.