EVERYDAY SCIENCE

Detailed explanation-1: -Cephalopods have the largest of all invertebrate nervous systems, with a brain weight-body weight ratio exceeding that of most fish and reptiles.

Detailed explanation-2: -An octopus’s brain-to-body ratio is the largest of any invertebrate. It’s also larger than many vertebrates, although not mammals. Octopuses have about as many neurons as a dog-the common octopus (Octopus vulgaris) has around 500 million.

Detailed explanation-3: -Cephalopods range greatly in size. The giant squids (Architeuthis species) are the largest living invertebrates; A. dux attains a length of more than 20 metres (60 feet), including the extended tentacles. The smallest cephalopod is the squid Idiosepius, rarely an inch in length.

Detailed explanation-4: -Among mollusks and even among all invertebrates, cephalopods have a large and complex brain that is highly centralized (Nixon and Young, 2003). The brain encircles the esophagus and is divided into 25 major lobes further subdivided in 37 or 38 lobes in octopods and decapods, respectively.

Detailed explanation-5: -The Complex Brain of Cephalopods The adult cephalopod brain has a typically invertebrate ganglia-like structure with densely packed neural cell bodies lying in the outer, perikaryal layer and branched processes and synapses centered in the neuropil (Matheson, 2002; Richter et al., 2010).