Ryan Photographic - Actiniaria - Sea anemones


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Order Actiniaria

 

The order Actiniaria comprises of the sea anemones. The common name, sea anemone. stems from a fancied resemblance to the terrestrial flower of the same name. Like all cnidarians, sea anemones possess toxic stinging cells with which they capture prey. Immobilized creatures are then drawn into the gastrovascular cavity and digested. Unlike most sea jellies, this cavity is sub-divided with septa which increases the absorptive area.

While typically sedentary, sea anemones are capable of slow movement and some can swim after a fashion. Indeed several species never attach to the substrate and drift upside down in the water column buoyed by a gas chamber at the base of their column. In my experience, several of the sand-dwelling sea anemones are capable of very rapid retraction under the sand if stimulated.

A few anemones host photosynthetic algae and obtain some of their energy requirements from their photosynthetic partners. A relatively small group of anemones (ten species) in the Indo-Pacific are hosts to various clownfish (mostly Amphiprion species). Because of the demand for clownfish and clownfish hosts these anemones have frequently been over-collected in some areas.

Sea anemones reproduce when males release eggs into the water which stimulates the females to release their eggs. In rock pools this can be quite impressive turning the water milky. Sea anemones can also reproduce by budding, splitting in half or sloughing bits of their pedal disk - a phenomenon known by the painful sounding name of pedal laceration.

 

Calliactis anemone species

Calliactis anemone species on Dardanus pedunculatus, Kri, Raja Ampat, West Papua

CNID 0418 Calliactis anemone species on Dardanus pedunculatus, Kri, Raja Ampat, West Papua.

Condylactis species

Condylactis species Raja Ampat West Papua

CNID 0488 Condylactis species Raja Ampat West Papua.

Cryptodendrum adhaesivum Adhesive sea anemone

Cryptodendrum adhaesivum, Adhesive sea anemone

CNID 0087Cryptodendrum adhaesivum, Adhesive sea anemone, Beqa, Fiji.

Edwardsia species Sea anemone

Edwardsia sea anemone New Zealand

CNID 0006 Edwardsia species sea anemone, Fiordland, New Zealand.

Entacmaea quadricolor Bulb tentacle anemone

Entacmaea quadricolor Bulb tentacle anemone, Kri Eco, Raja Ampat

CNID 8826 Entacmaea quadricolor Bulb tentacle anemone, Kri Eco, Raja Ampat.

Heteractis magnifica Magnificent sea anemone

Heteractis magnifica Fiji

CNID 0008 Heteractis magnifica Fiji.

Heteractis magnifica Magnificent sea anemone tentacle detail, Kadavu, Fij

CNID 4914 Heteractis magnifica Magnificent sea anemone tentacle detail, Kadavu, Fij

Lebrunia danae Branching anemone

Lebrunia danae Branching anemone Belize

CNID 0001 Lebrunia danae Branching anemone Belize

Lebrunia danae Branching anemone detail Belize

CNID 0002 Lebrunia danae Branching anemone detail Belize.

Mimteridium cryptum

Mimteridium cryptum Group

CNID 0003 Mimteridium cryptum group, Fiordland, New Zealand.

Phylctenactis tuberculosa Wandering anemone

Phylctenactis tuberculosa wandering anemone

CNID 0004 Phylctenactis tuberculosa wandering anemone, New Zealand.

Stichodactyla mertensii Merten's sea anemone

Stichodactyla mertensii Merten's sea anemone

CNID 0005 Stichodactyla mertensii Merten's sea anemone.

 

 

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