Knowra Ecdysozoa Ecdysozoa Ecdysozoa is a major animal clade whose members grow by periodically shedding an external cuticle or exoskeleton. It includes arthropods, nematodes, and several smaller groups.
Ecdysis : Ecdysis is the periodic shedding of an animal’s outer covering to allow growth or development. This molting process gives Ecdysozoa its name and marks its defining shared trait.
Ecdysteroid : Ecdysteroids are steroid hormones that regulate molting and development in arthropods. In arthropods, these hormones trigger the coordinated changes that begin ecdysis.
Arthropoda : Arthropoda is an animal phylum with segmented bodies, jointed appendages, and a chitinous exoskeleton. It is the most species-rich ecdysozoan lineage, including insects, crustaceans, and arachnids.
Ecdysozoan hypothesis : The ecdysozoan hypothesis proposes that molting animals form a shared evolutionary clade. It names the evolutionary proposal that brought these diverse molting lineages together.
Panarthropoda : Panarthropoda is a clade comprising arthropods, onychophorans, and tardigrades. Its members form a prominent subgroup within Ecdysozoa.
Cuticle : A cuticle is a nonliving outer layer secreted by an animal’s underlying tissues. Ecdysozoan cuticles are shed and replaced as the animal grows.
Ecdysis-triggering hormone : Ecdysis-triggering hormone is a neuropeptide that helps initiate the behavioral sequence of arthropod molting. It helps coordinate the final shedding actions after a new cuticle forms.
Nematoda : Nematoda is a phylum of unsegmented, cylindrical worms that possess a collagen-rich cuticle. Nematodes are a major ecdysozoan lineage despite lacking arthropod-like limbs.
18S ribosomal RNA : 18S ribosomal RNA is a component of the small ribosomal subunit used in molecular studies of eukaryotes. Early comparisons of this molecule supplied influential evidence for Ecdysozoa.
Scalidophora : Scalidophora is a clade of marine ecdysozoans that includes priapulids, kinorhynchs, and loriciferans. It groups several small-bodied lineages often overlooked in broad accounts of Ecdysozoa.
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