Sirenia facts for kids
Quick facts for kids SireniaTemporal range: Early Eocene – Recent
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| West Indian Manatees (Trichechus manatus) | |
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Sirenia
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The Sirenia, often called sea cows or sirenians, are a group of amazing mammals that live only in water. They are fully herbivorous, meaning they eat only plants. You can find them in warm places like swamps, rivers, coastal waters, and wetlands.
Today, there are four types of sirenians. They belong to two main families: the Dugongidae (which includes the dugong and the extinct Steller's sea cow) and the Trichechidae (which includes manatees). Some ancient sirenian families, like the Protosirenidae and Prorastomidae, are now extinct.
Sirenians are related to elephants and hyraxes! They all belong to a larger group called Paenungulata. Sirenians first appeared about 50 million years ago during a time called the Eocene period. The dugong family and the manatee family split into separate groups later, during the late Eocene or early Oligocene.
Sirenians are big animals. They can grow to be about 2.5 to 4 meters (8 to 13 feet) long and weigh up to 1500 kilograms (3,300 pounds). The largest sirenian ever was the extinct Steller's sea cow. It could reach lengths of 8 meters (26 feet) and weigh 8 to 10 metric tons (about 17,600 to 22,000 pounds)!
These animals have a smooth, torpedo-shaped body. This shape helps them move easily through the water. Their bones are very heavy, acting like weights to help them stay underwater. Sirenians have a thin layer of fat, so they don't like cold water. They often travel to warmer places when the water gets too chilly.
Sea cows usually swim slowly, around 8 kilometers per hour (5 miles per hour). But they can swim much faster, up to 24 kilometers per hour (15 miles per hour), for short bursts! They use their strong lips to pull up seagrasses and other plants. They eat a lot, consuming 10 to 15% of their body weight every day!
When they need to breathe, sirenians just poke their nostrils out of the water. Sometimes, they even stand on their tails to do this! They mostly live in warm, shallow coastal waters or rivers. While they mainly eat plants, they have been seen eating small animals like birds or jellyfish sometimes.
Male sirenians often mate with more than one female. They also take good care of their young.
Sadly, sirenians face many dangers. People sometimes hunt them for their meat, oil, bones, and skin. Other threats come from human activities like habitat destruction, getting caught in fishing gear, and being hit by boats. The Steller's sea cow became extinct in 1768 because of too much hunting.
Types of Sirenians
Here are the different types of sirenians, both living and extinct:
- Order Sirenia
- Family Dugongidae (Dugongs and their relatives)
- Dugong, Dugong dugon (The only living species in this family)
- †Steller's sea cow, Hydrodamlis gigas (This species is extinct)
- Family Trichechidae (Manatees)
- West Indian manatee, Trichechus manatus
- African manatee, Trichechus senegalensis
- Amazonian manatee, Trichechus inunguis
- Family Dugongidae (Dugongs and their relatives)
Images for kids
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This chart shows how different sirenian groups developed over time.
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See how the bodies of sirenians changed as they evolved.
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Dugongs search for seagrasses on the seafloor.
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West Indian manatees in a project to help protect them in Brazil.
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A baby Amazonian manatee being cared for by the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA).
See also
In Spanish: Sirenios para niños
