Neotenous origins for pelagic octopuses

Neotenous origins for pelagic octopuses

The 'ctenoglossans' are an enigmatic group of transparent, pelagic octopuses that spend their entire life without touching the seafloor. Molecular and morphological evidence shows that the ctenoglossans have arisen via neoteny, the persistence of larval attributes in the adult form. The ctenoglossans have evolved from the planktonic early-dispersal stages of familiar benthic octopuses. Extreme ...

Octopuses

What are they? Octopuses and their relatives, the cuttlefish and squids, form the class of modern cephalopods (coleoids). These are soft-bodied molluscan invertebrates like garden snails or sea hares (Aplysia). The modern cephalopods appeared in the sea at the same time as bony fish; more than 200 million years ago. The old cephalopods are virtually extinct — their only living representative is...

Single-session learning by octopuses.

Visual Discrimination of Distance by Octopuses

If two stimuli are presented to an octopus simultaneously, but at different distances from the animal, the nearer of the two is usually attacked. This preference was used to test the ability of octopuses to discriminate distance. White discs, 37 mm in diameter, were used as stimuli, and two parameters were varied: the distance of the farther stimulus from the animal (D), and the difference betw...

Detour Experiments with Split-brain Octopuses

Octopuses will make detours down an opaque corridor in order to reach crabs initially visible but not directly accessible to them (Wells, 1964). The situation can be used to investigate the function of parts of the brain in short-term learning and in interocular transfer. In a previous account the effects of removing the vertical lobe were considered. If this lobe is removed from the visual lea...