Renilla koellikeri

Geographic Range

Common along the Atlantic, Gulf, and southern California coasts of the United States existing in near-shore waters. Some species range as far south as Chile.


Renilla Kollikeri occur in the tropical near-shore waters on soft bottoms. The stem -like base of the polyp is anchored in the sand or mud ground.

Physical Description


The colonies consist of elongated axial polyps, which bud secondary polyps on their exposed surface.

  • Parental Investment
  • no parental involvement


Renilla are almost entirely colonial. Behavioral studies indicated that bioluminescence, polyp withdrawal, and contraction of the rachis are coordinated by a colonial through-conducting system, which is suspected to be of nervous nature.

Food Habits

Renilla feed on small animals and larvae, stinging and swallowing them after they become entangled in a mucous net secreted over the surface of the sea pansy. Food is first digested by septal filaments followed by intracellular digestion.

Economic Importance for Humans: Positive

Renilla are themselves eaten by nudibranch mollusks, one of the few animal groups with a taste for coelenterates. Renilla kollikeri has been the subject of much zoological and neurobiological research because of its possession of complex physiological properties such as highly developed neurotransmitters.

Economic Importance for Humans: Negative

No significant negative importance; stinging capsules are very small and cannot penetrate the human skin.

Conservation Status

Renilla are most commonly found along the Atlantic, Gulf, and Pacific coasts of the United States. Related forms are known from the Red Sea, Australia and other coastal areas.

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

Renilla, named for its kidney shape and violet color, may also be heart shaped. When transferred to a clean sea water and left undisturbed, disks of Renilla may expand to several times their contracted size and polyps may open. When suddenly disturbed, the portion of colony bearing the polyps is swept by waves of bright blue, violet, green, or yellow luminiscence. Renilla luminisces at night.


Takako Onishi (author), University of Michigan-Ann Arbor.


Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map


the nearshore aquatic habitats near a coast, or shoreline.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).


Anctil, Michel. et. al. 1987. Bioactivity of FMRFamide and related peptides on a contractile system of the coelenterate Renilla Kollikeri. Journal of Comparative Physiology, 157: 31-38

Anctil, Michel. 1984. Catecholamines in the coelenterate Renilla Kollikeri. Cell and Tissue Research, 238: 69-80

Barnes, Robert D. 1987. Invertebrate Zoology, Saunders College Publishing, Fort Worth, 135-138pp

Buchsbaum, Ralph and Milne, J. Lorus. The Lower Animals, Doubleday and Company, New York, 103pp

Carlberg, M. 1988. Catecholamines and chemically related amino acids in coelenterates. Neurobiology of Invertebrates, Akademiai Kiado, Budapest, 25-27pp

Kaestner, Alfred. 1964. Invertebrate Zoology, Interscience Publishers, 137-139