Actinoidea – Definition & Meaning

Actinoidea is a term that is commonly used in the field of biology. It is a term that is used to describe a group of marine animals that are characterized by their radial symmetry. These animals belong to the phylum Echinodermata, which includes starfish, sea urchins, and sea cucumbers. In this article, we will explore the definition and meaning of Actinoidea, its origin, associations, synonyms, antonyms, and examples of its usage.

Definitions

Actinoidea is defined as a group of marine animals that have radial symmetry. These animals have a central disc from which radiate arms or rays. They are also known as sea stars or starfish. The term Actinoidea is derived from the Greek word “aktis,” which means ray or spoke, and “eidos,” which means form or shape.

Origin

The origin of Actinoidea can be traced back to the early Paleozoic era, which was around 540 million years ago. The first fossil evidence of these animals dates back to the Ordovician period, which was around 485 million years ago.

Meaning in different dictionaries

Actinoidea is a term that is commonly used in the field of biology. It is defined in different dictionaries as a group of marine animals that have radial symmetry. The Oxford English Dictionary defines Actinoidea as “a group of echinoderms, including the starfish, characterized by radial symmetry and a central disc from which radiate arms or rays.”

Associations

Actinoidea is associated with the phylum Echinodermata, which includes starfish, sea urchins, and sea cucumbers. These animals are found in marine environments all over the world. They are important members of the marine ecosystem and play a vital role in maintaining the balance of the ecosystem.

Synonyms

The synonyms of Actinoidea include sea stars, starfish, and Asteroidea. These terms are used interchangeably to refer to the same group of marine animals.

Antonyms

There are no antonyms of Actinoidea as it is a specific term used to describe a group of marine animals that have radial symmetry.

The same root words

The same root words as Actinoidea include “aktis,” which means ray or spoke, and “eidos,” which means form or shape.

Example Sentences

1. The Actinoidea are important members of the marine ecosystem.
2. The sea stars, which belong to the Actinoidea, have five arms that radiate from a central disc.
3. The Actinoidea have radial symmetry, which allows them to move in any direction.
4. The Asteroidea, which is another name for the Actinoidea, are found in all the world’s oceans.
5. The Actinoidea have a unique ability to regenerate their limbs if they are lost due to predation or injury.