These species also cover ecologically diverse life histories, representing benthic, nectobenthic and nectonic animals. Cephalopods are animals with Vandetanib mechanism of action advanced cognitive skills and a complex repertoire of behavioral abilities [3,45]. Their brains are comparable both in size and complexity with those of vertebrates, and have been the focus of a number of studies on the neurobiology of behavior . In particular, they have served as models for the cellular and systems circuitry of learning and memory [4,9]. Historically, Octopus vulgaris has been a key species for this work through studies of anatomy , behavior following lesions and brain stimulation [3,4,47] and cellular neurophysiology [48,49]. O. vulgaris has also served as an attractive model for neuroendocrine studies in invertebrates [5,50].
Recently, Octopus bimaculoides (California Two-spot Octopus) has emerged as a model system for cephalopod biology. The large size of O. bimaculoides eggs grants unique access to early embryonic stages, making this species a prime candidate for future genetic and developmental studies. The hardiness, ready availability in the United States and easy husbandry of adult O. bimaculoides  add to the appeal of this model species. The deadly venom of blue-ringed octopus Hapalochlaena maculosa makes this species of interest for study of the evolution and regulation of toxicity within octopods . Comparative studies of these octopus species would illuminate the bases of both their shared characteristics as well as those of their divergent features.
Additionally, these species have essentially non-overlapping geographic distributions, providing animal accessibility to cephalopod researchers globally. Within the decapodiforms, Sepia and Loligo are the most studied genera. Historically, Sepia officinalis has been a key cephalopod for neurobiological research, and is a critical species in global fisheries. S. officinalis possesses a complex chromatophore network for countershading, camouflage and communication [3,52,53]. Its internal calcified shell supplies buoyancy and the effect of global climate changes on this structure has become a focus of recent study [54,55]. S. officinalis is emerging as a particularly versatile model organism in eco-evo-devo studies . As a practical matter, S. officinalis eggs are voluminous, and easily collected, maintained and reared in the laboratory .
The morphological events in S. officinalis embryogenesis are well described in the literature [58-61]. Loligo, and particularly its giant fiber system, has served as the fundamental basis for our understanding of nerve impulse conduction. The GSK-3 giant synapse system has recently been employed as a biomedical model of neurological disease . Loligo is one of the most important groups for cephalopod fisheries in the North Atlantic .