This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
The Monograph of the Gymnoblastic or Tubularian Hydroids. Plate XXI. Ectopleura larynx Hydrozoa Anthoathecatae Capitata Tubulariidae hydranth from male colony with its long simple racemes of gonophores magnified hydranth from female colony with its shorter compound racemes of gonophores magnified an entire natural size portion