Squillidae Family of Mantis Shrimp

Tiburon Mantis Shrimp, Squilla tiburonensis

The Squillidae Mantis Shrimp are Crustaceans in the Phylum Arthropoda and members of the Squillidae Family. They are in the Class Malacostraca. This Class is defined by having 5 head segments, 8 thoracic segments, and 6 abdominal segments. The head and thorax are usually combined as a cephalothorax. The head includes a pair of antennae, a pair of antennules, and mouth parts. These animals have stomachs with 2 chambers. They range in size from 1 cm (0.4 inches) to 48 cm (18 inches).

All Mantis Shrimps are in the Order Stomatopod. They are named for the resemblance of their “arms” and stalked eyes of Praying Mantis insects. They have eyes that are among the most complex in the animal kingdom that can see the full range of visible light colors, as well as ultraviolet and polarized light. The Stomatopods have 15 classes of photoreceptors; humans have 4 classes.

Stomatopods are separated into 2 categories based on the second pair of thoracic appendages – Spearers and Smashers. Spearers have barbed appendages that they use to spear soft prey such as fish. Smashers have a thickened portion at the “elbow” of the appendage and they strike hard shelled prey with a force equal to that of a small caliber bullet. This force breaks the shell and usually kills their prey instantly. The speed at which stomatopods move this second appendage is among the fastest movement of any animal, often completing the action in five to eight milliseconds. The next 4 pairs of thoracic appendages are subchelate (pincer-like) and are used for handling food and for burrowing. The last 3 pairs are used for walking. The uropods and telson comprise the tail fan.

Stomatopods are found worldwide, in tropical to sub-Antarctic waters with most found on tropical coral reefs and within soft substrates in shallow water, though some are found at depths exceeding 1,500 m (4,920 feet). Some species can form pelagic swarms. They may be nocturnal or diurnal and feed on cnidarians, crustaceans, fish, and mollusks. In turn they are preyed upon by fish and octopus. Some have the ability to generate a fluorescent display that is used to signal others of their kind, and, perhaps, other species. Some species of Mantis Shrimps are monogamous, sharing the same burrow with their partner for more than 20 years. There are around 480 species of Mantis Shrimp, divided into 17 Families of which 8 are represented along the Pacific Coast of Mexico.

The Mantis Shrimp of the Squillidae Family are “spearers”. They are characterized by T-shaped eyes with bi-lobed corneas and a well-developed, longitudinal, dorsal, carinae (keel). They have fixed, submedian teeth on a quadriform telson and rounded posterior angles on the carapace. They have six barbs on their second thoracic appendage (raptorial claw). They are found in “U”-shaped burrows in soft-substrate, or under rocks on soft substrate. Most live in shallow, temperate waters, but some are found as deep as 500 m (1,640 feet). There are 194 species in the Family, the largest family of stomatopods, that have been placed in 46 genera, in the Squillidae Family with 25 species being found along the Pacific Coast of Mexico. They are caught in abundance by shrimp trawlers and sold commercially.