Scientists are studying cephalopods' large brains, elaborate sense organs, and complex behavior in order to understand more about learning and behavior patterns in all species. Sepioteuthis sepioidea is among the species being studied. (Hanlon and Messenger 1996, New 1995)
US Federal List: no special status
CITES: no special status
Sepioteuthis sepioidea does not compete with humans for food or for habitat and consequently do not affect humans negatively in any respect. (New 1995)
All types of squid, including the species S. sepioidea, are particularly important to humans as a food source. Squid have little other significant economic importance for humans. (New 1995)
The diet primarily inculdes fishes (most of which are schooling sardines) and arthropods (usually shrimp floating near the surface at night). Squid eat on fish proportional to their own size. Very few fish larger than 12 cm are ever eaten; most are only a few centimeters in length. Presumably, S. sepioidea eat many planktonic animals that have not been recorded because they cannot be seen with the human eye. No available list of their prey is all inclusive since feeding patterns are derived entirely from observations made in the field.
S. sepioidea track food entirely by sight, which limits their feeding. They use body color changes to express emotion as well as to confuse or distract potential prey. Their tentacles remain hidden except during strikes when they extend the tentacles to bend upward and produce a hooklike effect.
It is not known upon what the semiplanktonic, newly-hatched squid feed. (Moynihan and Rodaniche 1982)
Sepioteuthis sepioidea lives in the ocean waters of Flordia and Bermuda through the West Indian islands and from Venezuela to Cozumel along the Caribbean shores of Central America and the northeast of South America. It lives in waters that are relatively clear and shallow to approximately 100 meters, with average salinity. It finds success and dominance in many localized areas of its range. (Moynihan and Rodaniche 1982)
Biogeographic Regions: atlantic ocean (Native )
The habitat of S. sepiodea changes according to the squid's stage of life and size. For ease of understanding, they will be divided into four size categories to help explain habitat preferences: very small (newly hatched), small, nonbreeding large, and large (breeding adult). The new hatchlings tend to reside in a very narrow range close to or between islands. Their habitat primarily includes areas from 0.2-1.0m below the surface on or under vegetation and 1-10m from the ocean bottom. These smallest individuals are found primarily during the day.
The small squid typically congregate in shallow turtle grass near islands and remain several centimeters to two meters from the surface to avoid bird predators. They also do not dwell on the ocean floor because of possible snapper predation. At night however, they often will swim to deeper waters and hunt with older, larger squid.
Nonbreeding adult S. sepioidea avoid the turtle grass flats of their younger years because of insufficient room to maneuver in these shallow waters. Most of the waters in the San Blas are home for these, including all varieties of ocean bottoms. They venture to depths of 100m and prefer open waters at night opposed to their shoreline home of their days.
Breeding and courting adults spend their days upon coral reefs of 1.5-8m depths. These large squid avoid all or most other habitats during this period.
Habitat Regions: saltwater or marine
Aquatic Biomes: pelagic ; reef ; coastal
The youngest individuals are semiplanktonic and swim rather passively due to their small, short fins. Their dorsal mantle is typically 8-9mm in length when they emerge from their eggs.
Adults of the species Sepioteuthis sepioidea resemble their close relative, the cuttlefish. They are less elongated, streamlined, and arrow-shaped than many other squids. Their triangular fins extend nearly the entire length of the body, which is a wide flattened viseral mass. Adult females' dorsal mantles reach lengths of at least 120 mm and males' reach at least 114 mm.
Their coloring is typically finely mottled, medium brown on the dorsal side and clear, light brown, or whitish on the ventral side. A distinct white line runs longitudinally on the dorsal side. Prominent brow ridges are above their large eyes. At night, individuals appear to be completely colorless because their pigment cells do not expand. It is not certain if this change in color at night has any significant purpose. (Moynihan and Rodaniche 1982)
Other Physical Features: ectothermic ; bilateral symmetry
The mating rituals of S. sepioidea are ambiguous and complex. Large adults typically form pairs of one female and one male before they disengage from the squid school to head for the reefs to mate. Most cephalopods, including the Caribbean reef squid, are semelparous; that is, individuals die after reproducing for the first and only time. Females lay eggs in clutches and die immediately after. However, males can copulate many times in a concentrated short period of time before they die. Females lay the eggs in well protected areas, scatterering them within the reefs, but do not care for the young in any direct way. It is advantageous for the male partner to escort the egg-bearing female to the reef in order for him to protect his investment from large carnivorous fish. (Hanlon and Messenger 1996)
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
