Mantis Shrimp

Mantis shrimps are crustaceans belonging to the order Stomatopoda, crab and related to lobsters relative sea. They differ from true shrimps and have persisted for approximately 400 million years. More than 400 species have been described today. The majority of these species are concentrated in the Indo-Pacific region, particularly around Australia.

Morphology and Appearance

Mantis shrimps range in size from 1 to 46 centimeters. Although most are between 1 and 30 centimeters, the largest recorded specimen measured 46 centimeters in length. Some species are notable for their vibrant colors, which can include red, green, blue, black and yellow hues. The peacock mantis shrimp (Odontodactylus scyllarus) is one of the species known for these colors. Other species include Squilla mantis, S. empusa, and Oratosquilla oratoria. Some species exhibit zebra-like patterns with cream and brown stripes.

Vision

Mantis shrimps possess one of the most complex eye structures in nature. Each of their stalked eyes is divided into three sections and can move independently. They can detect light across a broad spectrum, from deep ultraviolet to far red. Their eyes are sensitive enough to detect polarized light and, according to some studies, biological changes caused by cancerous cells.

Mantis Shrimp Eyes (Great Barrier Reef Foundation)

Habitat and Distribution

They live in coastal areas and on the seafloor, down to depths of 1,500 meters. Most species nest in coral reefs, crevices, and burrows. Some species prefer sandy or muddy substrates. Burrowing behavior contributes to the oxygenation of seafloor sediments.

Hunting and Feeding

Mantis shrimps have evolved specialized raptorial appendages for capturing prey. These appendages occur in two main forms: spearers and smashers.

• Spearers: Use pointed, barbed appendages to catch soft-bodied prey such as worms, fish, and shrimps.

• Smashers: Strike hard-shelled prey like snails and crabs with hammer-like appendages.

These strikes occur at speeds of up to 23 meters per second and with accelerations of approximately 10,400 g. The speed of the appendage is equivalent to the muzzle velocity of a 22-caliber bullet. During the strike, cavitation bubbles form, generating both heat and sound waves. Complex layered structures in the coup enable these powerful impacts to occur without injuring the shrimp. This mechanism has inspired designs in engineering for armor and sports equipment.

Behavior and Defense Mechanisms

Most species are solitary. However, some species live in pairs for their entire lifespan. When threatened, they display a defensive behavior known as “meral spread,” in which they expand their bodies and open their raptorial appendages to appear more intimidating. Physical attacks are used only as a last resort. In physical defense, the most striking feature of mantis shrimps is their fists.

Reproduction and Development

During mating, the male transfers sperm to the female, who stores it until her eggs are ready to be laid. The eggs are glued together by a sticky substance secreted by the female and protected during incubation. Larvae begin hunting using club-like structures approximately nine day after hatching. Some species are monogamous and remain with a single partner for life together.

Mantis Shrimp with Eggs, Image: Ocean

Ecological Role and Relationship with Humans

Mantis shrimps regulate species balance in their ecosystems as predators and enhance biodiversity. Their burrowing activities also influence the physical and chemical structure of the seafloor. Environment are sensitive to pollutants and can therefore serve as bioindicators in coral reef environments. Some species are harvested for human consumption, particularly in Japan, the Mediterranean, and coastal regions of North America. They can also survive in aquariums when appropriate conditions are provided.

Daily Activity and Species Diversity

Mantis shrimps may be active during the day or night depending on the species. Both larvae and adults are strong swimmers. Species diversity continues to expand, with new species still being discovered.