The sea is as near as we come to another world.

ANNE STEVENSON

Sea Anemones

Sea Anemones


The ornately colored sea anemone is named after the terrestrial anemone flower. A close relative of coral and jellyfish, anemones are stinging polyps that spend most of their time attached to rocks on the sea bottom or on coral reefs waiting for fish to pass close enough to get ensnared in their venom-filled tentacles.
 
Their bodies are composed of an adhesive pedal disc, or foot, a cylindrical body and an array of tentacles surrounding a central mouth. It only takes a very slight touch to trigger a reaction from the tentacles. Once touched the tentacles shoot harpoon-like filaments into the prey and inject a paralysing neurotoxin. The tentacles then guide the helpless prey into the sea anemone's mouth.
 
There are more than 1,000 sea anemone species found throughout the world’s oceans at various depths, although the largest and most varied occur in coastal tropical waters. They run the full spectrum of colors.
 
Some anemones have established symbiotic relationships with green algae. In exchange for providing the algae safe harbor and exposure to sunlight, the anemone receives oxygen and sugar, the bi-products of the algae's photosynthesis.

Sea anemones can reproduce either by sexual reproduction or by lateral fission. Lateral fission involves sprouting an identical sea anemone from the adult's side.

Deadly Anemones


The first mass extinction was caused by sea anemones. The first complex life-forms on earth, the Ediacarans, happily hung around on the sea floor for 37 million years until the Cambrian Explosion saw the number and variety of life forms suddenly rocket. Research by the University of Toronto on trace fossils from this period showed no evidence of any natural catastrophe but found that this explosion included the arrival of some sea-anemone-like creatures (which were predatory and mobile). This novel development of predators and the rapid disappearance of Ediacaran trace fossils suggested they probably ate all the largely immobile Ediacarans.

Prior to the Ediacarans, things had been even more dull – indeed the era is known as the 'Boring Billion' - a period of a billion years where not much happened. Blue-green cyanobacteria had evolved and were living nicely on the CO in the atmosphere, gradually releasing oxygen, but apart from that nothing else much went on. Specifically, evolution is said to have stalled. 

EMMA HART WILLARD (1787-1870)

Rocked in the cradle of the deep.

Fishy Friend


Anemones form a famous symbiotic alliance with clownfish, which are protected by a mucus layer that makes them immune to the anemone's sting. Clownfish live within the anemone’s tentacles, getting protection from predators, and the anemone snacks on the scraps from the clownfish’s meals. Clownfish groom the anemone, eating dead tentacles and attract fish to the anemone because they are so bright and colourful.
 
Anemones can survive without clownfish, but clownfish cannot survive without anemones.  Clownfish are never found in nature outside their host. If experimentally released away from their base they are quickly eaten by predators.

Actiniform means 'shaped like a sea-anemone'.

In Tobian, the clownfish is called ritchuh fa toh mari 'little fish in sea anemone'.

The sea anemone eats food and sends waste out through the same opening, so its mouth is also its anus.

Some species of sea anemone can grow to 1.8 metres across.

Boxing Clever


Boxer Crabs encourage stinging anemones to grow on the end of their pincer legs, and then use them as weapons to fight each other, their predators and immobilise their prey.

Anemone means 'daughter of the wind' in Greek.