Marine Mammals

Sperm
Whale

Sperm Whale
(12 votes)

The sperm whale (scient. Physeter macrocephalus) is a unique species of mammal found throughout the globe. Especially in the Mediterranean, most whales, some hundreds, live in the very deep waters south of Crete (especially south of Sougia).

Only a few Greeks know that in Greece there are whales, even though Aristotle had recorded their existence. It is noteworthy that south Crete is the only place in the world where one can admire the whales all over the year and is the point where they are believed to reproduce.

In Crete happens something unique in the world. The sperm whales reproduce continuously, and their social groups (females and the youngsters) and the lonely males are together throughout the year. This does not happen anywhere else in the world. Perhaps the Mediterranean sperm whales found here very good conditions, thus they ceased migrating for reproduction. Indeed, the main reason for the high concentration of whales in the region seems to be the enormous depths of the region, since a few miles from shore the depth reaches 2000m, while between Crete and the Peloponnese it reaches 5120m. This part (Greek Abyss) is abundant in large squids, the beloved food of whales.

The sperm whales look like common whales, but they have teeth (instead of whalebone), so they are closely related species to the dolphins. To feed on squid, the sperm whales dive to depths 500-1000m for 25-60 minutes (males) and for 20-24 minutes (females), although the deepest dives recorded are close to 2000 m and for 2 hours. The whales live for 70 years or more. Males reach a length of 18m and a weight of 57 tonnes. (12,5m and 24 tonnes for females).

Similarly, males are sexually mature in their 18-21th year (although they usually begin mating at 30 years), while for females it is 7-13 years. The gestation period of sperm whales lasts 14-16 months and they give borth to one baby whale.

The females, along with the youngsters, form social groups, usually with 10-14 individuals, while males live lonely. Generally, male sperm whales approach social groups to reproduce only once every three years, but only in Crete, they are always ready to reproduce.

The sperm whales are considered endangered in the Mediterranean Sea, mainly because of surface fishing nets. They are very thin, almost invisible nets, spanning a length of several kilometers to catch tuna and swordfish. Efforts are currently made for limiting their use in this area. Also, a great threat for the species seems to be the noise pollution caused by intense maritime traffic in the Mediterranean. Sometimes the sound of ships, confuses their sensitive hearing and crash to ships.

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