An ethogram of body patterning behavior in the biomedically and commercially valuable squid Loligo pealei off Cape Cod, Massachusetts

Squids have a wide repertoire of body patterns; these patterns contain visu al signals assembled from a. highly diverse inventory of chromatic, postura l, and locomotor components. The chromatic components reflect the activity of dermal chromatophore organs that, like the postural and locomotor muscle s, are controlled directly from the central nervous system. Because a thoro ugh knowledge of body patterns is fundamental to an understanding of squid behavior, we have compiled and described an ethogram (a catalog of body pat terns and associated behaviors) for Loligo pealei. Observations of this spe cies were made over a period of three years (less than or equal to 440 h) a nd under a variety of behavioral circumstances. The natural behavior of the squid was filmed on spawning grounds off Cape Cod (northwest ern Atlantic) , and behavioral trials in the laboratory were run in large tanks. The body pattern components-34 chromatic (including 4 polarization components), 5 p ostural, and 12 locomotor-are each described in detail. Eleven of the most common body patterns are also described. Four of them are chronic, or long- lasting, patterns for crypsis; an example is Banded Bottom Sitting, which p roduces disruptive coloration against the substrate. The remaining severe p atterns are acute; they are mostly used in intraspecific communication amon g spawning squids. Two of these acute patterns-lateral Display and Mate Gua rding Pattern-are used during agonistic bouts and mate guarding; they are v isually bright and conspicuous, which may subject the squids to predation; but we hypothesize that schooling and diurnal activity may offset the disad vantage presented by increased visibility to predators. The rapid changeabi lity and the diversity of body patterns used for crypsis and communication are discussed in the context of the behavioral ecology of this species.