Thursday, November 15, 2007

Distribution

And where do all these amazing species live? Well, the short answer is that we don't really know for sure. As will be the case for most of these posts, the majority of data available is on Taningia danae though there is limited information on some Octopoteuthis species.

Taningia is unique among the cephalopods in that it appears to have an almost worldwide distribution encompassing a variety of habitats. Most distribution data comes from stomach content analysis of sperm whales, once a highly exploited species. Beaks of T. danae have been recovered from the whales in the western North Atlantic, off Bermuda, Hawaii, South Georgia, South Africa, Japan, Australia, New Zealand, and the Azores. Thus, its geographical distribution can be described as cosmopolitan to the exclusion of polar regions (they tend to prefer warm, temperate, and sub-boreal waters).
Beaks in the stomach of a sperm whale (Source).

Taningia is typically a mesopelagic squid though they will venture into deeper bathypelagic waters, especially for spawning. Kubodera et al. (2007) found adult individuals over a range of depths from 240 to 940 m. The squid were observed to frequent deeper waters during the day. At night, squid were found in shallower waters (240 - 650 m), having completed a vertical migration to follow their migrating mesopelagic prey. Taningia can be found in all major ocean basins, in central waters, near oceanic islands, and near continental slopes.
Distribution map for T. danae (Cephbase.org).

Specimens of most Octopoteuthis species are pretty scarce, and thus distribution maps yield few patterns. The distribution of O. deletron has been described as confined to temperate Pacific Ocean habitats. This species tends to be found in the Eastern North Pacific, from off Baja California to Alaska and off northern Peru and possibly off eastern Honshu. Members of Octopoteuthis are all thought to be mesopelagic residents, undergoing vertical migration similar to T. danae.
Distribution map for O. megaptera (Cephbase.org).

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