So I asked leading shark ethologist and behaviourist, Professor Samuel 'doc' Gruber to elaborate. After pointing out how much pain women feel when they give birth, making the point that suffering has no effect on reproduction, he reminded me that sharks evolved their mating behaviours and the physical structures involved, separately from other animals.
Scientists used to think that only mammals and birds experienced different sleep states. More recent research, however, has revealed some reptiles and cuttlefish -- another cephalopod and relative of the octopus -- show non-REM and REM-like sleep.
A new study has found that the octopus has ‘quiet’ and ‘active sleep’, with different episode duration and periodicity, and experiences active sleep after a long episode of quiet sleep.
So as the Year of the Shark in 2019 begins, here is a review of how their actions reveal some of their mental states.
While many sharks are solitary predators, some are known to live in groups and are suspected of engaging in complex social behaviors. Meanwhile others simply aggregate due to similar habitat, food, or mating requirements.
Using a novel tagging procedure, scientists in the United States, have discovered that some shark species like to spend their time mixing and chilling out together.
A study by researchers from University of Milano-Bicocca describes observations of adults carrying dead calves and juveniles in 7 toothed cetaceans (odontocetes). The observation was based on 14 events from 3 oceans. The seven species studied were Indo-Pacific bottlenose dolphins, killer whales, Australian humpback dolphins, sperm whales, Risso’s dolphins, short-finned pilot whales, and spinner dolphins.
A difficulty in obtaining information about the natural behaviour of wild animals is that detailed observations of the activities of different individuals is necessary over long periods of time, and this is especially hard to achieve with sharks.
Abernethy, owner and operator of Scuba Adventures in Florida, had gained the shark's trust through gentle touches, initially to remove five hooks from her mouth. Since 2003, he has been using this method to remove hooks from many different species of sharks, as described in this former article about him, here.
Researching the intelligence of the grey bamboo shark a team of researchers at Rheinische Friedrich-Wilhelms-University in Bonn, Germany showed that sharks could be trained to recognise and remember shapes for an extended period of time.
First juvenile sharks were subjected to three different cognition experiments, one at a time, and then tested to see how long the sharks could remember their training.
A difficulty in obtaining information about wild animal behaviour is that detailed observations of different individuals is necessary over long periods of time, and this is especially hard to achieve with sharks. But in the shallow lagoons of French Polynesia, such observation was possible without the encumbrance of scuba gear, and without the problem of the shark disappearing into the depths.
Jim Abernethy, owner and operator of Scuba Adventures, was the dive operator who showed all of the others that sharks are peaceful animals who want nothing to do with humans as a food source.
He spends most of his time with wild sharks during dives from his liveaboard ship, The Shear Water, at remote sites in the vicinity of the Bahamas, and is on land for only about 40 days a year.
Excerpts from Current Biology, Volume 22, Issue 20, R860-R861, 23 October 2012
The whale lived among a group of dolphins and socialized with two female white whales. The whale was exposed to speech not only from humans at the surface -- it was present at times when divers used surface-to-diver communication equipment.
