a sperm whale

A sperm whale calf swims near the surface in waters off Dominica. Image by Brian Skerry/National Geographic-Pristine Seas

As the largest animals on Earth, whales need a lot of space. Even though their ocean habitat is vast, many whale species are impacted by human activities. Pollution, being hit by ships, and getting tangled up in fishing nets are all problems for whales.

Sperm whales are impressive animals

Sperm whales are the largest of the toothed whales. (They are also one of the largest species of whales overall.) An average male sperm whale grows to be about 15 meters (50 feet) long — this is about three times longer than a giraffe’s height. A male sperm whale can weigh up to 45 metric tons, about 90 times as heavy as a grand piano.

The sperm whale has the largest brain in the animal world! A sperm whale brain weighs about 8 kilograms (18 pounds) – that is heavier than a bowling ball.

A sperm whale swims beneath sargassum in waters off Dominica. Image by Brian Skerry/National Geographic-Pristine Seas

Sperm whales are deep divers – they plunge 1,000 to 2,000 m (3,300-6,600 ft) underwater to search for squid to eat. During these deep dives, sperm whales can hold their breath for about 90 minutes.

Sperm whales form strong family units, or clans. Each member communicates through the same language of click patterns. Whales within the same family may babysit for each other. Newborn whales may be nursed by their mothers as well as aunts, grandmothers, or other females within the clan.

Dominica is an important home for sperm whales


Dominica’s shore. “The 200 or so sperm whales that call our sea home are prized citizens of Dominica,” Roosevelt Skerrit, Dominica’s prime minister, said in a statement. Image by Manu San Félix/National Geographic-Pristine Seas.

Dominica is a tiny island nation in the eastern Caribbean Sea. A group of less than 300 endangered sperm whales live off the island’s coast. They are part of the whale group called the Eastern Caribbean clan. Dominica is creating a special reserve to protect these magnificent sperm whales.

Why do the sperm whales need protection? The sperm whales around Dominica are threatened by getting tangled in fishing gear, and also by pollution, boat strikes, and even tourism. Tourism can be a danger if boats get too close to whales and disrupt their feeding or how they care for their young.

A sperm whale calf swims with two adults whales in waters off Dominica. Image by Brian Skerry/National Geographic.

The Dominica sperm whale reserve will be about half the size of London, England. It will be 788 square kilometers (304 square miles) in size.

“The 200 or so sperm whales that call our sea home are prized citizens of Dominica,” said Roosevelt Skerrit, Dominica’s prime minister. “Their ancestors likely inhabited Dominica before humans arrived. We want to ensure these majestic and highly intelligent animals are safe from harm and continue keeping our waters and our climate healthy.”

The reserve will help protect sperm whales by introducing strict rules for boat traffic. It will designate routes for ships that avoid areas where the whales hang out. Tourism activities – like whale watching and swimming with whales – will be allowed to continue, but in limited numbers.

The Dominican government will monitor the reserve to ensure that the rules are being followed and that the sperm whales are being protected.

This story has been adapted for Mongabay Kids by David Brown. It is based on this article by Elizabeth Claire Alberts: