Red Sea fauna – Sea anemone (General Features – feeding habits – reproduction)

Photo credit: To a gentleman who I met once and it is shame to miss his name (thanks friend for the collection you shared with me years ago and forgive my weak memory)

Review: Abdel Rahman El Gamal

General Features: Even though the photo is comparable to “North Red Sea anemone” it safer to describe the general issues on sea anemones. Anemones are named after terrestrial flower “anemone”. There are more than 1,000 sea anemone species throughout the world’s oceans. The group of this described has a smooth, deep-red to purplish column with short, thick, and well-spaced tentacles. The tentacles have a variety of dark and pale color combinations resulting in variety of colors. The anemone has a heavy pedal column that is usually used in attaching the anemone to the substrates. An anemone uses its pedal disk (or foot) to release itself from the substrate and swim away in emergency situations such as predator avoidance. They can also move is by inflating themselves, detaching from the surface, and then rolling along with any current. The mouth of the anemone is located in the center of the oral disc. Both oral disc and mouth are usually pale in color, with each tentacle’s base being outlined with red. The life span of this anemone is relatively long as some specimens lived for up to 80 years.

Feeding habits: Like most of sea anemones, this species use its tentacles that are equipped with venomous cells (or nematocysts). Upon the touch, the tentacles are triggered and a harpoon-like structure is launched and attached to the source of the touch (prey), then, the anemone through its nematocysts stings the victim with a dose of venom (paralyzing neurotoxin) which immobilizes the prey before guiding it by the tentacles towards the mouth. The small fish and shrimp are the common food of anemones. Sea anemones have a gastrovascular cavity which means that the mouth used for food intake acts as anus as wastes and uneaten parts of the food are expelled through the same opening.  The neurotoxin used to capture the prey is also used by the anemones against any possible threats or attacks.

Reproduction: anemones reproduce sexually and asexually. In sexual reproduction, males release sperm and females release eggs through the mouth. Once fertilization occurs, the fertilized egg develops into a planula, which settles and grows into a single polyp.

The asexual reproduction occurs by longitudinal fission through which the polyp separates into two halves and pedal laceration, in which small pieces of the pedal disc break off and regenerate into small anemones.

Red sea fauna - Sea anemone


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