THE ANIMAL FILES

Waratah anemone

Actinia tenebrosa

A flower-shaped animal that folds with the tide.

The waratah anemone changes its outline dramatically between immersion and exposure.[1]

Follow the evidence ↓
Waratah anemone
Image: Toby Hudson · Commons · CC BY-SA 3.0
Changing outline
Tentacles extend underwater[1]
Rocky shelters
Crevices and overhangs[1]
Young close to home
Brooding and local clusters[1]

Changing outline

Underwater, numerous tentacles open in several rings. When exposed to air, they retract and the body closes into a rounded mound.[1]

Rocky shelters

This anemone lives on rocky shores of Australia and New Zealand, including crevices, boulder undersides and overhangs.[1]

Young close to home

This species can brood young inside its body cavity and release developed offspring through the mouth. Young often settle close to the parent, producing local clonal clusters. Sexual reproduction can also disperse larvae farther away.[1]

A COMMON MIX-UP

Does a closed mound mean this is a different species?

Not necessarily. Retraction changes the visible shape of the same animal. Compare its state and setting before interpreting a different silhouette as a different identity.[1]

TRY A LITTLE REASONING

Why might neighbouring anemones share a local origin?

Reveal the explanation

Brooded young can settle near their parent and form clonal clusters. Distance between individuals alone therefore does not establish whether they are unrelated or independently dispersed.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Waratah anemone (cited revision)
  2. NCBI Taxonomy — Actinia tenebrosa

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