Tardigrade facts for kids
Quick facts for kids Tardigrada |
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| The tardigrade Hypsibius dujardini | |
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Tardigrada
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Tardigrades, commonly known as 'water bears' or 'moss piglets', are tiny, water-dwelling animals that belong to the phylum Tardigrada. The name "water-bear" comes from the way they walk, reminiscent of a bear's gait.
They have been found in diverse regions of Earth's biosphere – mountaintops, the deep sea, tropical rainforests, and the Antarctic.
Contents
Physical Characteristics
- Shape: Tardigrades have a cylindrical body divided into four segments, each with two legs equipped with tiny claws.
- Size: They can range in size from 0.05 mm (newly hatched) to 1.2 mm (largest adults).
Diet
Tardigrades primarily feed on plant cells by piercing the cell walls and consuming the contents. Some species are carnivorous.
Reproduction
Tardigrades are oviparous. Tardigrades tend to court before mating. Courtship is an early step in mating and was first observed in tardigrades in 1895. Mating occurs during the molt with the eggs being laid inside the shed cuticle of the female and then covered with sperm.
The eggs hatch after no more than 14 days, with the young already possessing their full complement of adult cells. Growth to adult size occurs by enlargement of the individual cells (hypertrophy), rather than by cell division. Tardigrades may molt up to 12 times.
Cell Structure
Tardigrades are eutelic, meaning all adults of the same species have the same number of cells, which can be as many as 40,000 in some species.
Habitats
Tardigrades can thrive in various environments, including:
Approximately 83% of known species live on land, while 17% are aquatic.
Survivability
Tardigrades are remarkable for their ability to survive extreme conditions that would be lethal to most animals. They can withstand temperatures close to absolute zero and above boiling point, surviving brief exposure to 151°C. Some can endure being frozen for over 30 years.
Interesting facts about tardigrades
- They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ('little water bear').
- In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada, which means "slow steppers".
- Scientists believe tardigrades diverged from their closest relatives in the Cambrian more than 500 million years ago.
- There are over 1,000 species of tardigrades.
- Tardigrades can survive more than ten years without water.
- They can also survive radiation, toxic environments, and severe impact events. To endure such extreme conditions, tardigrades slow down their metabolism significantly.
- In 2007, some tardigrades survived 10 days in space, enduring vacuum and high radiation.
- In 2019, tardigrades on a lander that crashed on the moon are believed to have survived and could potentially live there for a few years.
Images for kids
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Hypsibius dujardini imaged with a scanning electron microscope
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Schematic reconstruction of four luolishaniids, possibly the closest known fossil relatives of modern tardigrades
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Reconstruction of Paradoryphoribius, a miocene tardigrade
See also
In Spanish: Tardigrada para niños
