Giant squid and sperm whale clashes: between myths and truth



by LORENZO CIOTTI

Giant squid and sperm whale clashes: between myths and truth

Sperm whales are able to dive up to 3 km deep and can remain on the ocean floor for up to 90 minutes. The most typical dives are around 400m deep, last 30-45 minutes and are generally done towards the north. They possess three tons of blood, which carries enough oxygen to aid them in their deep dives; thus they can go twenty times deeper than a human can.

They feed on a wide range of species, especially giant squid, octopus, and various different species of fish, such as deep-sea rays and some shark species, but the bulk of their diet consists of medium-sized squid. Almost everything we know about deep-sea squid has been gleaned from specimens found in the stomachs of captured sperm whales.

The tales of titanic battles between sperm whales and giant squid, which are believed to reach 13 m, are perhaps the result of legends, given that even the largest giant squid weigh only 300 kg, negligible weight compared to even a few tons of a young sperm whale specimen.

Although recently a 495kg colossal squid was caught by New Zealand fishermen in the Ross Sea. However, the white scars on the bodies of sperm whales are believed to be caused by squid or the teeth of other males. Giant squid is considered the main diet of sperm whales.

Thefts of pollack and nototenids caught with gillnets are well known, and also well documented. It is believed that this characteristic is also typical of other whales or small ones. It is hypothesized that the sharp beaks of consumed squid, contained in the intestine of the whale, induce the production of ambergris, similarly to the production of pearls.

The irritation of the intestines caused by the beaks stimulates the secretion of this lubricant-like substance. Sperm whales are extraordinary eaters, ingesting food totaling 3% of their body weight each day. The annual prey consumption of sperm whales around the world is estimated to be 100 million tons - as much as the weight of marine animals consumed annually by humans.

The only predator that attacks sperm whales, besides humans, is the orca. Large roving pods of orcas frequently attack groups of females and calves, usually trying to separate the baby sperm whale and kill it. Often female sperm whales can repel these attacks, forming a circle with their young in the center and then violently flapping their tails, thus preventing orcas from penetrating the formation.

If the pod of killer whales is extremely large, they may sometimes kill even adult females. Large male sperm whales have no predators, as even killer whales can be killed by these aggressive and powerful creatures. Fishing trips with gillnets in the Gulf of Alaska have recorded that numerous sperm whales took advantage of them, feeding on the fish left attached to the hooks, thus saving these whales from hunting operations.

However, the amount of fish thus obtained is very small compared to the daily food requirement of the sperm whale. Recent video footage has been captured of a large male sperm whale raiding a gillnet to earn some fish.