Orthonectida facts for kids
Quick facts for kids Orthonectids |
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Orthonectida
Giard, 1877
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Orthonectids are tiny, simple animals that live as parasites inside other sea creatures. They are so small that you need a microscope to see them! Even though they are multi-cellular (meaning they have many cells), they are some of the simplest animals on Earth. Scientists don't know much about them yet, which makes them very interesting to study.
What are Orthonectids?
Adult Orthonectids look like tiny worms. They are so small you can only see them with a microscope. Their bodies are very simple, with just one layer of cells on the outside. Inside, they have special cells that help them reproduce.
These tiny worms live inside other marine animals. They swim freely inside their hosts. Their hosts can be different kinds of sea creatures, like flatworms, polychaete worms, bivalve molluscs (like clams), and echinoderms (like starfish).
Orthonectids have separate male and female individuals. This means there are boy Orthonectids and girl Orthonectids.
Life Cycle and Reproduction
When Orthonectids are ready to have babies, the adult males and females leave their host animal. The male Orthonectid releases sperm, which then enters the female's body. This is called fertilization, and it creates a new baby cell called a zygote.
The zygote grows into a tiny larva. This larva has tiny hairs called cilia that help it swim. The larva then leaves its mother and swims around to find a new host animal.
Once the larva finds a new host, it changes. It loses its cilia and becomes a special kind of larva called a plasmodium. This plasmodium then breaks into many small cells. Each of these small cells grows into a new adult Orthonectid, starting the cycle all over again!
Orthonectids in Science
Orthonectids were first described by scientists in 1877. At first, they were grouped with another type of simple animal called rhombozoans. Both groups were put into a larger category called Mesozoa.
However, recent studies show that Orthonectids are quite different from rhombozoans. Scientists are still learning about these unique creatures. Their simple bodies and interesting life cycle make them important for understanding how complex animals evolved.
See also
In Spanish: Ortonéctidos para niños
