Otter Bliss?

Studies on captive otters have been carried out attempting to determine why they 'juggle' stones and pebbles (https://www.theguardian.com/science/2020/may/06/tummy-rumbles-otters-juggle-pebbles-probably-when-peckish). This is a common activity in otters whether the species largely feeds on fish or prefers bivalves and crabs. The author suggests that increases in juggling are stimulated by hunger, as the activity increases in intensity as the time since a feed is extended. Most of the subjects studied were Eurasian short-clawed otters. This species is more social than the European otter (making it attractive to zoos); subjects had a very limited ability to range (being confined to enclosures) and were fed on items perhaps atypical of their normal diet. Rock juggling may thus be one of the activities that the subjects could easily do to fill their day (perhaps it is a form of environmental enrichment?). It is tempting, however, to see the otter's rock juggling (sea otters use rocks as tools to break open shells) as equivalent to humans jiggling their cutlery at the table before the food is served.