File:American malacological bulletin (1988) (18157725751).jpg

Title: American malacological bulletin
Identifier: americanmal6719881990amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
40 AMER. MALAC. BULL. 7(1) (1989) 5mm ft
Text Appearing After Image:
Fig. 54. Hectocotylus, third right arm modified for spermatophore transfer. Fig. 55. Copulation. Male is at the top and female at the bottom. Arrow indicates the hectocotylus of the male inserted into the female's mantle cavity. seen as early as 30 days. The various components of the eye generally begin to appear between days 40 and 60. The Deimatic pattern is fully expressed at about day 100 and the typical form of Passing Cloud was not observed until day 210. However, it is likely that the animals are capable of express- ing it before this time. Copulation was not seen before six months of age. At the end of the life cycle senescence sets in and the skin begins to deteriorate. Most of the components and patterns are affected during senescence, and the common body pat- tern at this period is a variant of Uniform Light Phase. LOCOMOTION AND EXPLORATORY BEHAVIOR Octopus briareus moves by four principal methods: crawling, backward swimming, backward medusoid swim- ming and forward swimming (Figs. 42, 43, 44). Hatchlings are capable of crawling and backward swimming. The animals usually only swim when they are excited, and they do so in the acute pattern Uniform Darkening and often squirt three or four pseudomorphs of ink as they move backwards. Medusoid swimming and forward swimming were only observed later in the life cycle. Exploratory behavior was common in octopuses of all ages. When an octopus is placed in a new tank or an object is placed in its home tank, the animal will usually first withdraw into the Protective posture and then soon investigate new ob- jects by extending one or several arms cautiously. The arms can stretch a great distance and the animal is thus able to use tactile and chemosensory organs in the suckers to ob- tain information about new objects. Eventually the animal will touch all objects in its tank and move around to investigate them more carefully. Octopuses also use vision in exploratory behavior. They will often lean in the direction of interest to obtain better sight of an object before leaving their lair. INTRASPECIFIC INTERACTIONS Octopus briareus is a solitary animal for most of its life cycle. During the first few weeks posthatching, the young animals tolerate conspecifics and sometimes even aggregate in group-culture conditions. However, they soon become in-

Note About Images