Hourglass dolphin facts for kids
Quick facts for kids Hourglass dolphin |
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Lagenorhynchus
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| Lagenorhynchus cruciger |
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The Hourglass dolphin, known scientifically as Lagenorhynchus cruciger, is a small and wide dolphin. It lives only in the very cold waters around Antarctica. This dolphin was first known to science from a drawing made in 1820. Scientists have only been able to examine six Hourglass dolphins. This is because boats do not usually travel to the very remote areas where they live. The average water temperature in their habitat is about 0.1 to 0.3 degrees Celsius, which is almost freezing!
The hourglass dolphin is black and white. Because of its colors, it was sometimes called the "sea skunk." On each side, it has a white patch that looks a little like an hourglass shape. This is how it got its common name.
An adult hourglass dolphin is about 1.8 meters (6 feet) long. It weighs between 90 and 120 kilograms (200-265 pounds). Only one other dolphin in this area is as small as the hourglass dolphin. Hourglass dolphins usually stay in groups of 5 to 10. However, one large group of 60 dolphins was once seen. They enjoy riding the bow waves of boats. They are often seen swimming with Fin whales. Scientists think they eat small fish, crustaceans (like crabs or shrimp), and squid. They have cone-shaped teeth that are probably used to crack the shells of crustaceans.
The hourglass dolphin stays around the Antarctic region. Some have been seen south of New Zealand and Chile.
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What Does the Hourglass Dolphin Look Like?
The hourglass dolphin is mostly black and white. Sometimes, it can have variations of dark grey. Each side of the dolphin has two white patches. One patch is at the front, near its beak, eye, and flipper. The second patch is at the back. These two white patches are connected by a thin white strip. This connection creates a shape that looks like an hourglass, which gives the dolphin its name.
The scientific name cruciger comes from Latin. It means "cross-carrier." This name refers to the black area on the dolphin's back. When seen from above, this black area vaguely looks like a Maltese cross or a cross pattée.
Scientists have not yet seen or studied any baby hourglass dolphins (calves). So, their exact colors are still unknown.
Comparing the Hourglass Dolphin to Other Dolphins
In its usual home range, the hourglass dolphin is easy to identify. Only the southern right whale dolphin is similar in size and lives as far south. However, the southern right whale dolphin does not have a dorsal fin (the fin on its back). This makes it easy to tell the two species apart.
The dorsal fin of the hourglass dolphin can look different from one dolphin to another. It is generally tall and curved. In older dolphins, the curve of the fin might be especially noticeable.
Size and Weight of Hourglass Dolphins
A fully grown adult hourglass dolphin is about 1.8 meters (6 feet) long. It weighs between 90 and 120 kilograms (200 to 265 pounds). Scientists believe that male dolphins might be slightly smaller and lighter than females. However, because so few specimens have been studied, this is not a definite conclusion.
How Hourglass Dolphins Find Food
Like all dolphin species, hourglass dolphins use echolocation. This is like using sound waves to "see" their surroundings. They send out sounds and listen for the echoes that bounce back. This helps them find food and communicate with other dolphins in their group, called a pod.
Where Do Hourglass Dolphins Live?
Hourglass dolphins live all around the Subantarctic region. Their range extends from close to the Antarctic ice pack up to about 45 degrees South. The most northern places where they have been seen for sure are 36 degrees South in the South Atlantic Ocean and 33 degrees South near Valparaíso, Chile, in the Pacific Ocean.
They are most commonly seen south of New Zealand, around the South Shetland Islands, and off Tierra del Fuego, Argentina. It is unlikely that many dolphins live very close to these land areas.
One study estimated that there are more than 140,000 hourglass dolphins in the world.
How Hourglass Dolphins Behave
Hourglass dolphins usually travel in groups of about 5 to 10 individuals. One study by the International Whaling Commission recorded a larger group of 60 dolphins. Some people have even reported seeing groups of up to 100.
They often share their feeding areas with other large sea animals. These include sei, pilot, bottlenose, and minke whales, as well as southern right whale dolphins. Hourglass dolphins are very often seen swimming with fin whales.
Hourglass dolphins are known for being very good at riding the bow waves of boats. This means they swim right in front of a boat, riding the wave that the boat creates as it moves through the water.
Scientists have studied the stomach contents of the few hourglass dolphins they have examined. This research shows that they eat different types of squid and small fish. The exact types of squid and fish are not yet known.
Images for kids
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A rare look at the hourglass dolphin.
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Hourglass dolphins leaping in the Drake Passage
See also
In Spanish: Delfín cruzado para niños
