Merten's Carpet Anemone
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Merten's Carpet Anemone

Merten's Sea Anemone, Non-Stinging Carpet Anemone, Spotted-Base Carpet Anemone

Merten's Carpet Anemone, Stichodactyla mertensii, Merten's Sea Anemone, Non-Stinging Carpet Anemone, Spotted-Base Carpet AnemoneStichodactyla mertensiiPhoto Wiki Commons, courtesy Silke Baron.
Licensed under Creative Commons 2.0 Generic

The large Merten's Carpet Anemone is host to a plethora of critters, from 12 species of clownfish to a variety of crustaceans!

The Merten's Carpet Anemone Stichodactyla mertensii is the true giant of the clown fish anemone hosts. The largest of the carpet anemones, it has a deeply folded oral disc that can grow to a diameter of up to 3.3 feet (1 m). They are named Carpet Anemones because they grow wide rather than tall and are so covered with tentacles that they look like a 'plush' carpet. The oral disc of the Merten's Sea Anemone is green, cream, or yellowish in color with tentacles tipped in white, yellow, or green. Its column is whitish or tan with sticky verrucae (bumps) that are tan, magenta, or orange. These adhesive verrucae, being under the oral disc edge, hold the disc in position.

Although the Merten's Carpet Anemone does not sport as many colors as other carpets, it is similar in overall appearance to the popular Saddle Carpet Anemone S. haddoni and the Giant Carpet Anemone S. gigantea. This often leads to confusion and mis-identification. An easy way to distinguish between them is by the environment where they are found. The Merten's is always in the midsts of rocky substrates or coral while the others are most often found in sandy areas.

Besides coloration, there are some visual characteristics to help identify each carpet species as well. The Merten's Carpet Anemone has less tightly packed tentacles and it can grow much larger than either of the others. Its oral disc is deeply folded, which differentiates it from the Saddle Carpet Anemone whose folds are less deep, lending a wavy appearance to the anemone. The Merten's Carpet Anemone often spreads out to blanket the surrounding substrate, while the Giant Carpet Anemone is rarely held flat against its surrounding surfaces. The Giant Carpet Anemone also has sticky tentacles while the Merten's does not.

The Merten's Carpet Anemone should only be kept by very experienced aquarists. Besides its large size, this is a much more delicate carpet anemone. In general they do poorly in the aquaiurm. They are rarely imported, but they need very dedicated care when they are.

For more information about Clown Fish anemones, see:
Facts About the 10 Clownfish Hosting Sea Anemones


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Merten's Carpet Anemone - Quick Aquarium Care
  • Minimum Tank Size: 100 gal (379 L)
  • Aquarist Experience Level: Expert
  • Temperament: Semi-aggressive
  • Temperature: 74.0 to 82.0° F (23.3 to 27.8° C)
  • Size of organizm - inches: 39.0 inches (99.06 cm)
  • Diet Type: Carnivore
  • Suitable for Nano Tank: No

Habitat: Distribution / Background

Sea Anemone Facts: The Merten's Carpet Anemone Stichodactyla mertensii was described by Brandt in 1835.  The Stichodactyla genus is a member of the Stichodactylidae family, and this genus contains 6 species. Some other names they are known for are Merten's Sea Anemone, Non-Stinging Carpet Anemone, and Spotted-base Carpet Anemone. The Stichodactyla mertensii is not on the IUCN Red List for endangered species.

Where are Sea Anemones Found: The S. mertensii is found in the Indo-Pacific Ocean from Comoros to the Fiji Islands.

Sea Anemone Habitat: These anemones dwell at depths of 3 to 66 feet (1 to 20 m). They live singly on coral rubble reefs and rocky walls. The anemone will hide most of its body in deep rock crevices or holes, with only the oral disc remaining above the substrate. It hosts a plethora of different clownfish and several other marine animals. They use their venomous cells or nematocysts found in their tentacles to sting and deflect any possible threats or attacks. Some predators can be other anemones, nudibranchs, sea stars and some angelfish, triggers and large wrasses.

  • Scientific Name: Stichodactyla mertensii
  • IUCN Red List: NE - Not Evaluated or not listed

Description

Appearance of a Sea Anemone: The Non-Stinging Carpet Anemone Stichodactyla mertensii has a pedal column that is often relatively narrow with a sticky foot which they use to adhere deep into rock crevices or holes. They also use this "foot" to move around if conditions are not ideal. The pedal column is whitish or tan with sticky verrucae (bumps) that are tan, magenta, or orange. These adhesive verrucae, being under the oral disc edge, hold the disc in position.

It has a deeply folded oral disc that is green, cream, or yellowish in color with tentacles tipped in white, yellow or green. The blunt finger-like tentacles are regular and mostly short, about 2 cm on the periphery with longer tentacles up to 5 cm around the mouth. However, there can often be patches of longer tentacles as well. The mouth should be closed and tight, and will open when hungry, having an oval look, yet a gaping mouth is a warning signal. The S. mertensii takes food in, and expels waste through this same opening.

Sea Anemones Life Cycles: The Merten's Carpet Anemone is the largest in this genus. They usually grow up to 39" (1 m), but according to Helmut Debelius and Hans A. Baensch, authors of 'Marine Atlas Volume 1 (Baensch Marine Atlas)', they can obtain diameters of up to 5 feet (1.5 m). It is unknown how long they live, some anemones can be hundreds of years old in the wild, and in captivity have been known to last decades. The S. mertensii have not been bred in captivity and rarely do they split on their own.

  • Size of organizm - inches: 39.0 inches (99.06 cm) - According to some sources they can reach 60 inches in diameter in the wild.
  • Lifespan: - It is unknown how long they live, but some anemones can be hundreds of years old in the wild, and in captivity have been known to last decades.

Difficulty of Care

Sea Anemone Care: The Spotted Base Carpet Anemone can be be difficult to care for because they do have high lighting needs and must be in a large enough aquarium to satisfy their ultimate size. They should only be kept by experienced aquarists as they tend to do poorly in the aquarium, so will need dedicated care. Putting an anemone in a new tank will result in failure. The tank should be at least 12 months old and stable before adding your new S. mertensii.

When choosing your anemone, make sure the color is good, their mouth is not gaping open, and their foot and tentacles are sticky to the touch. Also, they should be attached to something and make sure there is no damage to the foot area, often a result of pulling the anemone off its surface.

To remove an S. mertensii from another aquarium when it is stuck on the glass, use a hair dryer. Blow at the foot of the anemone from the outside of the tank and the heat will make it pull away. If it's attached to a rock, ideally you can simply purchase the rock as well. If you cannot purchase the rock then use ice cubes in a zip lock bag, and gently rub the foot all around until it releases. This may take a few minutes, but it is the most reliable way of getting your anemone to release. Don't allow the fresh water of the ice cubes to touch the foot directly as this can cause tissue damage.

  • Aquarium Hardiness: Difficult to Impossible
  • Aquarist Experience Level: Expert

Foods and Feeding

What Do Sea Anemones Eat: The Merten's Carpet Anemone is a carnivore. Stichodactyla anemones are well equipped with nutritional alternatives for their well-being. In the wild they derive daily nutrition from their symbiotic algae, zooxanthellae, that dwells within their tissues. They also use their venomous cells or nematocysts found in their tentacles to sting and capture prey. This is usually to blind prey like urchins, snails, crabs, shrimps, as well as small fish that come into range. They absorb nutrients from the water around them and they consume wastes from resident animals like clownfish. For their well-being it is not necessary for them to be fed by Clownfish they host, though clowns will often carry chunks of food to the anemone.

In captivity you can feed your S. mertensii chopped silversides, cod, and other types of fresh chopped fish (from your grocery store), as well as frozen carnivore preparations. Some say they are not always keen on crustacean flesh, but it is a natural food for them in the wild. You can offer table shrimp, clams, and mussels if yours will accept it. It is sufficient to feed them 2 to 4 times a week, and this avoids overfeeding.

Clownfish hosted with your anemone usually will not be able to sufficiently feed themselves and their anemone with the small quantity of food that is put in a captive environment. You will need to target feed this anemone. You can just offer your clowns a piece of fish flesh and they will usually snatch it out of your hand and give it to their host. However, not all clowns are this smart, so don't depend on the clown fish to feed the anemone.

  • Diet Type: Carnivore
  • Meaty Food: All of Diet - They can be fed chopped silversides, cod, and other types of fresh chopped fish (from your grocery store), as well as frozen carnivore preparations. You can also offer table shrimp, clams, and mussels if yours will accept it.
  • Feeding Frequency: Weekly - Feed them 2 to 4 times per week.

Aquarium Care

Water changes of 10% bi-monthly or 20% a month are typical. Monitor your water quality for your particular situation and adjust your water changes accordingly. A Merten's Carpet Anemone (6" to 8") is equal to 3 or 4 fish as far as waste production is concerned. A good protein skimmer is a must.

Purigen and Poly-fiber are great products to help in maintaining water quality. Purigen is a synthetic polymer that removes soluble and insoluble impurities from water at an exceptionally high rate and capacity, helping to control ammonia, nitrites, and nitrates. Additions of Iodine are suggested. Keeping salinity stable with a top off mechanism is highly suggested. Control phosphates with products such as Phosban and the Phosban reactor.

  • Water Changes: Bi-weekly
  • Iodine Levels: - Additions of Iodine are suggested.

Aquarium Setup

The typical live rock/reef environment is what is needed for a Merten's Carpet Anemone. They need live rock or dead coral with deep crevices to bury their foot into. Once it is secured, if it is happy it will stay put. If it isn't happy and is moving around, be sure to check your lighting and water quality. Also make sure you are feeding it adequately. With all anemones it's a good rule of thumb to have all of your pumps covered, most good quality pumps have guards on them.

  • Minimum Tank Size: 100 gal (379 L)
  • Suitable for Nano Tank: No
  • Live Rock Requirement: Typical Amount
  • Substrate Type: Any
  • Lighting Needs: Moderate - normal lighting - Moderate to high.
  • Temperature: 74.0 to 82.0° F (23.3 to 27.8° C)
  • Specific gravity: 1.023-1.025 SG
  • Water Movement: Moderate - Moderate to high water flow.
  • Water Region: Bottom - Bottom or middle of the aquarium, where there are cracks to bury their foot in.

Social Behaviors

All anemones are semi-aggressive because they can be mobile, although a contented Merten's Sea Anemone will stay put once it has found a place to settle. It has often been suggested to not put anemones in a reef environment because corals cannot move away from the stinging tentacles. Once you have your anemone situated and it has not moved for several months, it might be safe to add other corals. Keep this in mind when stocking sessile inverts. Some predators can be other anemones, nudibranchs, sea stars and some angelfish, triggers and large wrasses.

With the Non-Stinging Carpet Anemone, it is generally recommended that you don't put any other anemones in the same tank. Anemones need to have their own space, otherwise there can be a "chemical" warfare between species. This will usually cause one to not eat, shrink, and eventually die. However, after splitting anemones will tolerate their own "clones", and sometimes their own species. Having excellent filtration and a large tank (over 200 gallons), will usually allow 2 anemones at opposite ends to thrive. You can also build a natural blockade to help prevent them from wandering into each others "space".

The Merten's Carpet Anemone is a clown hosting anemone, known to host up to 12 different clown fish species. It has also been known to associate with crustaceans including the Porcelain Crab Neopetrolisthes ohshimai. An interesting fact is that three of these clownfish; the Clark's Clown fish Amphiprion clarkii, Orange-fin Clownfish A. chrysopterus and the Three-Band Clownfish, A. tricinctus will be black (melanistic) when hosted by this anemone.

If you want to have your Merten's Carpet Anemone host a clownfish, be sure your anemone is 3x's larger in diameter than the length of the clown fish you introduce.

It has been known to host the following 12 Clownfish species in nature:

  • Venomous: Yes
  • Temperament: Semi-aggressive
  • Compatible with:
    • Same species - conspecifics: Sometimes
    • Anemones: Monitor
    • Mushroom Anemones - Corallimorphs: Monitor
    • Leather Corals: Monitor
    • Shrimps, Crabs, Snails: Monitor
    • Starfish: Safe
    • Crabs: Monitor
    • Snails: Monitor
    • Nudibranch, Sea Slugs: Monitor

Sex: Sexual differences

No sexual difference in appearance is known.

Breeding / Reproduction

The S. mertensii have not been bred in captivity and rarely do they split on their own. Propagating is not recommended. Anemones in general can multiply by sexual and asexual means. One way is using fission, which is when they actually split in half from the foot or mouth to form a clone, although the clone is its own animal, similar to twins. They will also reproduce using male and female sex glands or find another anemone of the opposite sex. This results in the production of ciliated planula larvae. This planula will eventually fall to the sea floor, develop a pedal disk, then begin to grow into a new anemone.

  • Ease of Breeding: Difficult

Ailments / Diseases

Problems for the Merten's Carpet Anemone are pretty minimal unless your lighting, water movement, feeding and water quality are low. Then your anemone will detach to look for "better conditions." In general, if your anemone moves, it is not happy. With any change in shape, color, or other indications that there is a problem, then you need to check your lighting and water quality. If there are any non-reef type fish in the aquarium, like large wrasses, look for possible attack marks. Some predators can be other anemones, nudibranchs, sea stars and some angelfish, triggers and large wrasses.

Availability

Buy A Sea Anemone: The Merten's Carpet Anemone S. mertensii is difficult to find in stores and online. They are a rare import compared to other carpet anemones.

References



Author: Clarice Brough CFS, Carrie McBirney
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