The Squilla mantis, commonly known as the speckled mantis shrimp, is a marine crustacean found predominantly in the Mediterranean Sea and parts of the Eastern Atlantic Ocean. Despite its common name, it is not a true shrimp but belongs to the order Stomatopoda, a distinct group of crustaceans. This creature exhibits unique adaptations that allow it to thrive as an ambush hunter in its specialized environment.
Physical Characteristics and Habitat
The Squilla mantis possesses an elongated, flattened body that reaches lengths of 12 to 20 centimeters. Its coloration is a dull brown, which aids in camouflaging it against the seafloor. Brown eye spots, encircled in white, are present at the base of its telson (tail segment).
The body is segmented, with a shield-like carapace protecting its cephalothorax and a broad abdomen fanning out towards the tail. Its large, raptorial appendages are folded beneath its head, resembling a praying mantis. They prefer shallow, coastal waters with sandy or muddy seabeds, constructing U-shaped burrows. Their geographic range extends across the entire Mediterranean coast and south into the Atlantic from the Gulf of Cádiz to Angola, including the Canary Islands and Madeira.
The Powerful Predatory Strike
The Squilla mantis is categorized as a “spearer” type of mantis shrimp. It uses its sharp, barbed raptorial appendages to impale soft-bodied prey with remarkable speed. These appendages pierce small fish and shrimp, which are then dragged back into the burrow.
The strike itself is one of the fastest movements observed in the animal kingdom, occurring in less than 8 milliseconds. While “smasher” mantis shrimp utilize a catapult mechanism for their powerful blows, larger spearers like Lysiosquillina maculata (a related species) primarily use muscle power for their strikes, though smaller spearers may employ a spring-loaded catapult. The speed of a spearer’s harpoon strike has been measured at approximately 2 meters per second.
Advanced Vision System
The Squilla mantis possesses one of the most complex visual systems known in the animal kingdom. Its eyes are mounted on stalks and can move independently, allowing for a wide field of view. Each eye is divided into three sections, including two flattened hemispheres and a specialized midband comprising six rows of visual units (ommatidia).
This unique structure enables trinocular vision within a single eye, providing depth perception without relying on both eyes working together. The eyes contain a high number of photoreceptor types, ranging from 12 to 16, compared to the three types found in human eyes. They perceive wavelengths from deep ultraviolet (300 nm) to far-red (720 nm), and detect polarized light, including circularly polarized light, an ability rarely documented in other animals. This advanced vision aids in distinguishing prey and predators in complex marine environments, especially where light scatters and becomes circularly polarized.
Diet and Ecological Role
As an ambush predator, the Squilla mantis waits within its burrow for prey before striking. Its diet primarily consists of soft-bodied animals such as small fish, smaller shrimp, marine worms, and other crustaceans, aligning with its “spearer” hunting style. They also consume mollusks and can exhibit cannibalistic behavior.
This species plays an important role in its local food web. As a predator, it regulates populations of smaller benthic organisms. Its burrowing activities contribute to the turnover and oxygenation of soft seabed sediments, influencing the local marine ecosystem. Despite being a predator, it serves as prey for larger marine animals, including various fish and octopuses.