Tag Archives: Anemone

Epiactis Prolifera: Brooding Anemone- The Race Rocks Taxonomy

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broodinganemone

A field of Epiactis prolifera, showing the high variability in colouration– photo by Ryan Murphy.

Brooding anemones or Epiactis prolifera are a small species: the height of an expanded specimen does not often exceed about 3cm. The basic colour is brown to greenish brown, but it is sometimes red, pinkish red or dull green. They are usually found in the subtidal zone (zero tidal zone), especially on intertidal rock benches or surge channels, and in rocky areas with wave action, often in areas with crustose coralline algae. Brooding anemones are also regularly found on the leaves of eelgrass. Red or pinkish red specimens are sometimes found on rocky shores, but rare on eelgrass. They are rarely exposed to the air, not being able to tolerate exposure to the air and sun. Brooding anemones, like other sea anemones, attach themselves to something solid so as not to get carried off by currents or wave action.

 

The oral disk of brooding anemone is generally marked with radially arranged white lines. The pedal disk and column have similar lines, though they may not be as sharp. The numerous young regularly found on the pedal disk do not originate there by asexual budding, but are derived from eggs fertilized in the digestive cavity. The motile larvae, after swimming out of the mouth, migrate down to the disk and becomes installed there until they become little anemones ready to move and be able to feed themselves. You can see the belt of juvenile anemone in several of the images above.

Domain Eukarya
Kingdom Animalia
Phylum Cnidaria
Class Anthozoa
Order Actiniaria
Family Actiniidae
Subclass Zoantharia
Genus Epiactis
Species prolifera
Common Name: Brooding Anemone
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Brooding Anemone photo by Ryan Murphy

Brooding anemones eat small fish and shrimps. Much of their prey is crustaceans. The brooding anemones capture its prey with its deadly stinging tentacles. Its mouth and tentacles are located on the top of its body. Their stalk and tentacles are bristling with an arsenal of stinging cells, or nematocysts. The double walled microscopic stinging cells contain a hollow thread with a minute harpoon-like barb at the end. When the cell is stimulated either physically or chemically, it explodes and fires the barb and attaches the thread with incredible force into the potential predator or prey and simultaneously injects a potent poison. Usually hundreds and thousands of these stinging cells are activated at once, which can paralyze prey or deter most predators.

After being immobilized, the prey which may include shrimps, crabs, jellyfish or small fish is manoeuvred by tentacles towards the mouth where it is consumed whole. Any indigestible material or waste will be excreted through the mouth as well. Even with its formidable arsenal of nematocysts, anemones are a favoured prey for other animals. Many nudibranchs feed on anemones and are not only immune to the anemones defenses, but have the ability to absorb un-detonated packets of stinging cells which are then used for the nudibranchs own defense. Sea stars and fish are also some regular predators. If a brooding anemone, like any other sea anemones, is torn apart, then each part becomes a new brooding anemone.

References:

Eugene N.Kozloff: Marine Invertebrates of the Pacific Northwest
Seashore Life of the Northern Pacific Coast
Megumi F.Strathmann: Reproduction and Development of Marine Invertebrates of the Northern Pacific Coast
Doug Pemberton: Divers Magazine February 2001
http://divermag.com/archives/feb2001/anemones-feb01.html
Sea Anemones: http://library.thinkquest.org/J001418/anemone.html

This file is provided as part of a collaborative effort by the students, staff, faculty and volunteers of Lester B. Pearson College February 2002 Sangeeta Asre- Fiji Islands
Year 28

Metridium farcimen: Giant Plumose Anemone–The Race Rocks Taxonomy

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Metridium cluster by Ryan Murphy

 

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The Metridum farcimen polyp can reach well over 30cm in length. Ryan Murphy photo

General description: The Giant Plumose Anemone is a fairly large anemone of typically white, cream, tan, orange or brown colourations. Subtidal animals can often reach 25cm in crown diameter and 50cm in height. However larger specimens have been reported around 75cm in height. Shape of the column is much longer than wide. Tentacles lining the mouth of the oral disk are quite fine, very numerous, slender and short. Tentacle colouration is typically transparent when the tentacles are expanded and take the colour of the column when contracted.Habitat: Found in both subtidal and low intertidal zones, including jetties, wharfs, harbours, breakwaters and floats. When found on wharfs, anemone communities of dense distribution are common. Larger specimens are often found solitarily in the subtidal. The Plumose Anemone ranges from Alaska to southern California and along both sides of America.

These images by Ryan Murphy show the biological associations of which they are a part.

 

Feeding: Both the small and large anemones feed primarily on zooplankton, using their stinging tentacles to catch the prey. The feeding appears non-selective. Scraps of fish and squid and small benthic (subtidal) organisms are also taken.

In this video Ben from Australia introduces us to this abundant anemone found in the waters around Race Rocks. Note the fine tentacles– ideal for trapping plankton in the high current areas. Also note that this is not Metridium senile as labelled, but Metridium farcimen 

Predators: The Plumose Anemone has few predators. Nudibranchs feed on small anemone, while in Puget Sound (Washington State) a sea star (Dermasterias imbricata) has been found to feed on larger anemones.

Reproduction: The anemone reproduces both asexually and sexually. Asexual reproduction occurs as the anemone moves about, leaving small sections of its pedal disk (base) behind, in a process described as pedal laceration. Dense colonies can be formed in this manner, with the pedal disks forming small cloned rounded anemones that feed and grow.

Sexual reproduction occurs in a broadcast spawning process whereby the males release sperm with wedged-shaped heads stimulating the females to release their eggs, about 0.1mm in diameter with a pinkish colouration. External fertilization occurs, with the zygote dividing to form a planula larva which swims in planktonic form. Adam Harding caught this process in action in July .

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Metridium spawning, Adam Harding photo.

 Planulae settle and metamorphose into young anemones.

Biotic Associations: Plumose Anemone symbiosis is an area in which little research has been done. Possible commensal behaviour may be similar to other anemones which have certain fish (e.g Clown Fish) which use the anemone.

Interesting behaviour: Anemones are rich in nematocysts (stinging cells) which are used in both defense and attack. The normal tentacles contain these cells used for both defense and feeding. However, in large colonies of Plumose Anemones the species bordering the colony develop a different type of tentacle; “catch” tentacles. These tentacles, which are used to repel non-cloned anemones, take about 9 weeks to develop close to the mouth and may number as great as 19 on an individual organism. If the “catch” tentacles, which contain a different type of nematocysts, touch another anenome from a separate colony a stinging tip breaks of and releases the separate complement of nematocysts. This technique is used to repel intruding anemones. Interestingly, these tentacles can expand to a possible length of 12cm.

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Domain Eukarya
Kingdom Animalia
Phylum Cnidaria
Class Anthozoa
Order Actinaria
Family Metridiidae
Genus Metridium
Species farcimen
Common Name: Giant Plumose Anemone

Reference: R.Morris, D.Abbott, E.Haderlie, Intertidal Invertebrates of California (690) pp. 62-63. Stanford University Press, Stanford, California. 1983.

 

Return to the Race Rocks Image Gallery and Taxonomy

This file is provided as part of a collaborative effort by the students, faculty, staff and volunters of Lester Pearson College UWC February 2002 Ben Dougall PC28

Anthopleura elegantissima: Aggregating Anemone-Race Rocks taxonomy

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Anthopleura growing in a moist crevasse. Photo by Ryan Murphy.

One of the many organisms found at Race Rocks are sea anemones. Sea anemones belong to the phylum known as the Cnidaria, from the cnida or stinging cells that are present in this major group of animals that also include corals, jellyfish, hydroids, medusae, and sea fans. Sea anemones, corals and their allies form the class know as the Anthozoa. Anthopleura elegantissima is abundant on rock faces or boulders, in tide pools or crevices, on wharf pilings, singly or in dense aggregations (Smith and Carlton, 1975)

 

 

 

 

 

anthopleur       Link to extended essay of Santiago on Anthopleura distribution in the intertidal zone.

 

 

 

 

maliha   Link to  the extended essay by Maliha Zahid on Anthopleura-elegantissima-Distribution

 

 

 

 

Kingdom Animalia
Phylum Cnidaria
Class Anthozoa
Subclass Zoantharia
Order Actiniatia
Family Actiniidae
Genus Anthopleura
Species elegantissima
Common Name Aggregating Anemone

 

Characteristics:

  • The aggregating anenome is 2-5 cm in column diameter and 4-5 cm high in its clonal form.
  • The tentacular crown is roughly 8 centimeters in diameter.
  • The species presents numerous short tentacles, in five or more cycles, which are variously colored.
  • At the bases of its tentacles are bulbous structures where certain types of stinging capsules are concentrated.
  • The column is light green to white, and twice as long as wide when extended, with longitudinal rows of adhesive tubercles (verrucae)
  • Rock, sand, and shell fragments accumulate on anenome by adhering to the tubercles on the column.
  • The anenome is a green or olive colour depending on the algae living in its tissues.

Habitat:

It is a species characteristic of middle intertidal zone of semi protected rocky shores of both bays and outer coast from Alaska to Baja California.

Reproduction:

Anthopleura elegantissima reproduces both sexually and asexually. In sexual reproduction, ova are present as early as February and grow steadily until their release in July; the ovarian is then resorbed and new eggs do not appear until the following February. Sperm are released through the summer. The asexual reproduction occurs by longitudinal fission. This process results in aggregations or clones of anemones pressed together in concentrations of several hundred per square meter.

Ecological Niche:

  • Anthopleura elegantissima is a carnivore, feeding on small crustacians such as copepods, isopods, amphipods, and other small animals that contact the tentacles.
  • It is preyed upon by the nudibranch Aeolidia papillosa, which usually attacks the column, by the nail Epitonium tinctum, which attacks the tips of the tentacles, and by sea stars such as Dermasterias imbricata that can engulf an entire small anemone.
  • Moreover, in some anemones, small pink amphipods, Allogaussia recondita, make a home in the gastro vascular cavity. Two types of unicellular algae live in the tissues ofAnthopleura elegantissima in a symbiotic relationship. It is these algae that give the anenome its distinctive green or olive colour.

Interesting Further Studies:

  • Ecological niche study was conducted by Santiago, Pearson College Student 1998-2000../../research/santiago/santiago.htm
  • The US Environmental Protection Agency (EPA) has investigated using aggregating anenome as a test for salinity. This bioindicator would be used to see the freshwater influx in ocean environments. http://es.epa.gov/ncer/fellow/progress/99/cohenri00.html
  • The behaviour of Anthopleura elegantissima at different depths.
  • The reproduction cycle of Anthopleura elegantissima.
  • Further study of aggregating anenomes at Race Rocks.

References:

  • Kozloff, Eugene N. Seashore Life of the Northern Pacific Coast. (Seattle: University of Washington Press, 1983).
  • Kozloff, Eugene N. Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and Adjacent Regions. (Seattle: University of Washington Press, 1974).
  • Morris, R.H. etal. Intertidal Invertebrates of California. (Stanford: Stanford University Press, 1980).