Caribbean Reef Squid, Sepioteuthis sepioidea

Caribbean Reef Squid, Sepioteuthis sepioidea. Underwater photographs taken in coastal waters of Yal-Ku, Quintana Roo, April 2016. Photographs courtesy of Juan Rojo, Akumal.

Phylogeny: The Caribbean Reef Squid, Sepioteuthis sepioidea (Blainville, 1823), is a member of the Lolignidae Family of Pencil Squid. The genus Sepioteuthis is one of ten genera in this family and there are three species in this genus. The genus name Sepioteuthis comes from the Greek words for “cuttlefish squid” because of these squids’ resemblance to cuttlefish. This is reinforced by the species name sepioidea which means “like a cuttlefish”. This species is also commonly referred to as the Reef Squid, and in Mexico it is known as Calamar de Arrecife.

Morphology:  Caribbean Reef Squid are less elongate, and more dorso-ventrally flattened than most squid, causing them to resemble cuttlefish. Their triangular fins run almost the entire length of their body. Their legs are shorter than their body. Their coloration is highly variable. Generally, in the daylight, their dorsal side is mottled brown, with a longitudinal white stripe. Their ventral side is a clear light brown to whitish. This counter shaded pattern helps to camouflage them against the ocean’s bottom and surface. When confronted by a predator they have the ability to turn pale, add a eye spot to confuse the predator, and jet away. Male squid have the ability to display a zebra stripe pattern to drive away competing males. Caribbean Reef Squid have a mantle that reaches a maximum of 12 cm (4.7 inches) in length.

Habitat and Distribution:  Adult Caribbean Reef Squid are usually associated with coral reefs during the day. Juveniles are often associated with nearshore patches of turtle grass. They are found from the ocean’s surface to depths up to 100 m (330 feet). At night, adults and juveniles both move into deeper, open water to hunt. They primarily consume fish and shrimp. The Caribbean Reef Squid is a tropical Western Atlantic species that has a limited distribtion in Mexican waters being found only in the coastal waters adjacent to the Yucatán Peninsula in both the Gulf of Mexico and the Caribbean.

Diet:  The Caribbean Reef Squid’s diet consists mainly of fish like the schooling sardines and arthropods like shrimp.

Predators: Caribbean Reef Squid are an important food source for sea birds, moray eels, sharks, and other fish such as barracuda, groupers, jack, snappers, and even parrotfish.

Reproduction: Caribbean Reef Squid are gonochoric (male or female for life). They reproduce sexually with indirect fertilization. The courting ritual of the Caribbean Reef Squid involves color and pattern changing communication, the female participates in sexual selection. If selected, the male attaches a packet of sperm to the females body while displaying a pulsating pattern. The female moves the sperm packet to her seminal receptacle and then lays her eggs. The eggs are laid in clusters of capsules. The eggs hatch into a planktonic larval stage. They reach sexual maturity in only five to six months. Like other cephalopods, the Caribbean Reef Squid is semelparous. Female squids die immediately after laying eggs, but the male can fertilize multiple females before dying.

Ecosystem interactions: Caribbean Reef Squid are know to host parasitic nematodes from the genus Anisakis, and Dicyemids (worm-like parasites that live in cephalopod renal sacks [kidneys]).

Human Interactions:  The Caribbean Reef Squid are fished commercially and sold as dried squid primarily in Southeast Asia. From a conservation perspective they are currently considered to be of Least Concern with stable, widely distributed, populations.

Synonyms:  Loligo sepacea, Loligo sepoidea, Sepia affinis, Sepia officinalis jurujubai, Sepioteuthis biangulata, Sepioteuthis blainvilliana, Sepioteuthis ehrhardti, Sepioteuthis occidentalis, Sepioteuthis ovata, Sepioteuthis sepiacea, and Sepiacea sloanii.