Christmas Anemone, Urticina crassicornis, , Painted Urticina, Northern Red Anemone
Urticina crassicornis

The Christmas Anemone is one of the beautiful Urticina anemones likened to “flowers of the sea!”

The colorful Christmas Anemone Urticina crassicornis is a common cold water anemone from the North Pacific. Other common names it is known by are the Northern Red Anemone, Christmas Sea Anemone, Mottled Anemone, Painted Urticina, and Painted Anemone. This anemone, along with a number of its Urticina cousins, are equated to “flowers of the sea” as they have very festive colors.

At first glance, the fancy Urticina anemones look very similar to one another. Some of the Christmas Anemones relatives that look much the same include the Painted AnemoneUrticina grebelnyi, Dahlia AnemoneUrticina felina, Fish Eating AnemoneUrticina piscivora, and the White-Spotted Rose AnemoneUrticina lofotensis. The Christmas Anemone is easily identified, however, because of its smooth column and the opaque, often colorful, tentacles.

Although the Urticina anemones can look quite similar to each other, each one has its own unique characteristic to identify it by. General common names include the Mottled Anemone, Painted Urticina, Northern Red Anemone, Painted Tealia, Red and Green Anemone, Northern Red Anemone, Dahlia anemone, and Thick-petaled rose anemone. Although these common names are often used interchangeably, there is one generally accepted common name for each species.

A unique characteristic of the Christmas Anemone is that it always has a smooth column. The column ranges in color from pale orange to reddish-brown, often contrasted with stripes or irregular patches. The oral disc is pale white or yellow, usually sharing the same solid color in the tentacles. The mouth is reddish and there are red radial bands outlining the base of each tentacle.

If you keep a cold water system, the Christmas Anemone is wonderful anemone variety to add to your display. It is moderately sized with the column being about 3†(7.6 cm) in diameter and the crown reaching about 10″ (25 cm) across. As long as its requirements are met it is easy to care for, but as a cold water species, it is a good idea to Invest in a chiller before you obtain one of these guys.

When caring for the Christmas Anemone, use similar husbandry as for other cold water anemones. Like all anemones, they use their venomous cells, or nematocyst found in their tentacles, to sting and deflect any possible threats or attacks. But they mostly utilize them for stunning and capturing prey. Be mindful of their tankmates, as they will eat small fish as well as sea urchins, crabs, and mussels. Some predators can be certain nudibranchs, sea stars, and snails.

For more facts about Urticina Sea Anemones, see:
Nettle Anemones

Christmas or Northern Sea Anemone, Urticina crassicornis

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Christmas Anemone feeding

The Christmas or Northern Sea Anemone has a few name that reflect the temperature of the waters they are found in…. cold! They are similar in appearance and stickiness of most “rock anemones” and are easy to feed. The challenge is keeping your tank between 50.0 to 68.0° F (10.0 to 20.0° C), provide enough light and good water movement. They are great in a cold water nano tank and are easy to feed!

Christmas Anemone – Quick Aquarium Care
  • Minimum Tank Size: 20 gal (76 L)
  • Aquarist Experience Level: Intermediate
  • Temperament: Semi-aggressive
  • Temperature: 50.0 to 68.0° F (10.0 to 20.0&deg C)
  • Size of organism – inches: 10.0 inches (25.40 cm)
  • Diet Type: Carnivore
  • Suitable for Nano Tank: Yes

Habitat: Distribution / Background

The Christmas Anemone Urticina crassicornis was described by O. F. Mueller in 1776. It was formerly called Tealia crassicornis. It is widely distributed and common in the North Pacific and other northern seas. This anemone is not on the IUCN Red List for endangered species. Some other common names they are known by are Christmas Sea Anemone, Northern Red Anemone, Mottled Anemone, Painted Urticina, and Painted Anemone.

The Urticina genus is a member of the Aiptasiidae family and currently contains 12 species. General common names the various Urticina anemones are known by include the Mottled Anemone, Painted Urticina, Northern Red Anemone, Painted Tealia, Red and Green Anemone, Northern Red Anemone, Dahlia anemone, and Thick-petaled rose anemone. These common names are often used interchangeably, but there is one generally accepted common name for each species.

Christmas Anemones are found in colder, intertidal waters down to about 98 feet (30 m). They inhabit vertical rock walls that are shaded, sand and rock covered shore lines, as well as tide pools. They are found solitary or in small groupings. Similar to other cold water tidal anemones, they retract their tentacles and close up if the water is sparse during low tides.

They use their venomous cells, or nematocyst found in their tentacles, to sting and deflect any possible threats or attacks. But they mostly utilize them for stunning and capturing prey. They eat prey similar to what other Urticina anemones eat such as sea urchins, small fish, crabs, mussels, gastropods, chitons, barnacles, and they may feed on stranded jellyfish.

  • Scientific Name: Urticina crassicornis
  • IUCN Red List: NE – Not Evaluated or not listed


The Christmas Anemone is a moderately large animal. It can grow up to 3†(7.6 cm) in diameter and reach as tall as 5†(12.7 cm) or more. Its oral disk is crowned with tentacles, and can extend about 10″ (25 cm) across. In the wild, these anemones can live between 60 to 80 years.

The Christmas Anemone has a very smooth column that is not sticky like other Urticina anemones. This is one characteristic which sets them apart from the other species. The color of the column ranges from pale orange to reddish-brown and can have contrasting colors of stripes, or irregular patches.

These anemones have a “foot†at the bottom of the pedal column that they use to adhere to various surfaces. They can use this foot to move around if conditions are not ideal. They can also move by inflating themselves, detaching from the surface, and then rolling along with any current. They will move to avoid predators like starfish, but in the aquarium they primarily move if they are unhappy with the water conditions or the food.

At the top of the column is an oral disc with an opening, or mouth, in the center. The U. crassicornis takes food in and expels waste through this opening. The mouth should be closed and tight. It will open when hungry, having an oval look. A gaping mouth is a warning signal that the anemone is not doing too well.

Tentacles are well spaced on the oral disc. They are situated in 5 or more rows surrounding the mouth. The oral disk is more pale than the column, and is white or pale yellow. The region around the mouth may be reddish colored. There are red radial bands that outline the base of each tentacle. The tentacles are usually the same color as the oral disk, and are solid with no markings.

  • Size of organism – inches: 10.0 inches (25.40 cm) – They can grow up to 3″ in diameter, as tall as 5″ in height, and have a crown reaching about 10″ across.
  • Lifespan: 80 years – They can live from 60 to 80 years in the wild, probably less in captivity.

Difficulty of Care

The Christmas Anemone is moderately easy to care for if you have appropriate lighting and cold water. Putting an anemone in a new tank will result in failure. As with most anemones, the tank should be at least 9 months old and stable before adding your new U. crassicornis.

When selecting a U. crassicornis, make sure the color is good, their mouth is not gaping open, and their foot and tentacles are sticky to the touch. They should also be attached to something. Make sure there is no damage to the foot area, as this is often a result of pulling the anemone off its surface.

To transfer a Christmas Anemone from another aquarium, use a very thin blunt item like a credit card to get under the foot. Slowly nudging it away will get the anemone off the glass. If its attached to a rock, ideally you can simply purchase the rock as well, because these guys can stick hard and would probably be damaged if removed. If you cannot purchase the rock, while under water, directing water at it or wiggling the rock gently upside down while tickling the foot can sometimes work.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate – Cold water species.

Foods and Feeding

The Christmas Anemone is a carnivore. In nature, they use their tentacles to sting and capture prey, often careless fish and invertebrates that bump into them. In captivity hand feed your U. crassicornis chopped silversides, shrimp, krill, and mussels, fresh chopped fish (from your grocery store), as well as frozen carnivore preparations.

The Christmas Anemones metabolism is not as fast as warmer water anemones. They are cooler water creatures, so usually only need to be fed once a week or twice a month.

  • Diet Type: Carnivore
  • Flake Food: Occasionally – Carnivore formula. Depends on individual tastes of the anemone.
  • Tablet / Pellet: Occasionally – Carnivore formula. Depends on individual tastes of the anemone.
  • Live foods (fishes, shrimps, worms): Some of Diet – From marine sources.
  • Liquid Foods: Some of Diet – Zooplankton.
  • Meaty Food: All of Diet – Sources of marine flesh and frozen/thawed preparations for carnivores.
  • Feeding Frequency: Weekly – Feed them once a week to twice a month.

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. Waste production created by your anemone can be calculated in inches. Basically, every inch of anemone is equal to an inch of fish, so an average-sized Christmas Anemone produces a bio-load equivalent to that of one or two 3″ fish.

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. Additional chemical additives, such Chemi-Pure, GFO, and carbon also help maintain quality water parameters. Poly-fiber can be cut and used in sumps, etc. A good protein skimmer is a must.

Although anemones are not as dependent on calcium as stony corals, magnesium and calcium is still needed to keep the pH and alkalinity stable and within the correct parameters. Additions of trace elements are suggested. Phosphates should be kept around 0.03 or less. Control phosphates with products such as Phosban and the Phosban reactor.

  • Water Changes: Bi-weekly
  • Calcium Levels: 380.0 – 450.0 ppm – Helps to balance alkalinity. Aim for 420 ppm, or 385 ppm if you are using Seachem calcium.
  • Alkalinity Levels: 7.0 – 11.0 dKH – (2.5 to 3.9 meq/L) Aim for 10 dKH (3.5 meq/l) for reef tanks.
  • Magnesium Levels: 1,250.0 – 1,350.0 ppm – Test magnesium levels and adjust before checking Calcium.
  • Strontium Levels: 5.0 – 15.0 ppm – Aim for 8 ppm.
  • Iodine Levels: – .030 to .060 ppm: Control is not recommended.

Aquarium Setup

The Christmas Anemone can readily be kept in a nano reef of just 20-gallons or more. The typical reef environment is needed, but it must be a cold water reef. They need live rock or some other solid material they can attach to. You can even use submersed bio-balls. Calcium doesn’t need to be as high in cold water, so providing reef rock for calcium is actually not necessary although it is needed to keep the alkalinity and pH stable.

Because bacterial formations take a very long time in cooler water, the most important thing for the nano reef is mechanical and chemical filtration. Provide a good skimmer and use filter floss and chemical additives, such Chemi-Pure, GFO, and carbon in the filter to help keep the water clean. Chemi-Pure helps remove heavy metals, copper, phenol, ammonia and other nitrogenous waste. It also helps keep the pH at a consistently safe range. Granular ferric oxide, or GFO, helps with phosphate control. Water changes when things get out of normal parameters, so the addition of a refugium with a deep sand bed can help maintain normal parameters, too.

They need a moderate to high-surge water movement and average lighting. The light emitted from LED and t5 fixtures puts off less heat, which is essential with a cold water tank. The temperature can be between 50 to 68° F (10 – 20° C), but whatever temperature you choose, keep it stable as fluctuations can be stressful to the anemone. A chiller will be needed, but this allows you to have both inter-tidal and sub-tidal animals. Acrylic tanks are best for insulating against temperature fluctuations, each 1/2″ will give a thermal barrier of 5° F. Be sure to have all of your pumps covered, most good quality pumps have guards on them.

  • Minimum Tank Size: 20 gal (76 L)
  • Suitable for Nano Tank: Yes
  • Live Rock Requirement: Typical Amount
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 50.0 to 68.0° F (10.0 to 20.0&deg C)
  • Specific gravity: 1.023-1.025 SG
  • Water Movement: Moderate – Moderate to high surge.
  • Water Region: Bottom

Social Behaviors

The Christmas Anemone is considered semi-aggressive because they can be mobile and split quite often once adjusted. It has often been suggested to not put anemones in a reef environment since corals cannot move away from the stinging tentacles. Most of the cold water anemones will stay still if their needs are met. They will move, however, if your lighting is not good or the water quality is not to their liking.

These anemones split quite often once they are settled. After splitting, however, they will tolerate their own “clones†and sometimes their own species. All anemones in the tank 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. Having excellent filtration and a large tank 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 “spaceâ€.

Christmas Anemones are best kept in a species specific display. Keeping corals in the tank can be a risky thing to do because these anemones multiply rather quickly once adjusted. If attempting to add cold water corals, allow the anemones to settle first. Once they are in place, you can then try placing a coral away from them. Because of the way they reproduce, however, there may eventually be detrimental affects on any other corals or anemones.

If the tank is very large, keeping larger cold water fish should be fine. Problems occur when keeping small gobies, blennies or other small cold water fish. These can easily become dinner if they wander into the very sticky (more sticky than typical) tentacles of this anemone.

Be cautious with other tankmates, too, as this beautiful anemone does eat many invertebrates that wander their way. Urticina anemones will eat crabs, mussels, barnacles, sea urchins, and even jellyfish. Interestingly, the Candy Stripe Shrimp Lebbeus grandimanus is immune to its sting and lives in a commensal relationship with it. Some predators, can be certain nudibranchs, sea stars and snails.

  • Venomous: Yes
  • Temperament: Semi-aggressive
  • Compatible with:
    • Same species – conspecifics: Sometimes – They will tolerate their own offspring.
    • Anemones: Monitor – Keep only with other cold water anemones.
    • Mushroom Anemones – Corallimorphs: Threat – This anemone will quickly multiply and sting tankmates.
    • Leather Corals: Threat – This anemone will quickly multiply and sting tankmates.
    • Zoanthids – Button Polyps, Sea Mats: Threat – This anemone will quickly multiply and sting tankmates
    • Sponges, Tunicates: Threat – This anemone will quickly multiply and sting tankmates.
    • Shrimps, Crabs, Snails: Monitor – The Candy Stripe Shrimp, Lebbeus grandimanus, is immune to its sting and lives in a commensal relationship with it.
    • Starfish: Threat
    • Feather Dusters, Bristle Worms, Flatworms: Threat
    • Clams, Scallops, Oysters: Threat
    • Crabs: Monitor
    • Snails: Threat
    • Sea Apples, Cucumbers: Threat
    • Urchins, Sand Dollars: Threat
    • Nudibranch, Sea Slugs: Threat
    • Copepods, Amphipods, Mini Brittle Stars: Safe
    • Stony Corals: Threat – is aggressive – This anemone will quickly multiply and sting tankmates.
    • Soft Corals: Threat – is aggressive – This anemone will quickly multiply and sting tankmates.

Sex: Sexual differences

No sexual difference in appearance is known.

Breeding / Reproduction

The Christmas Anemone will divide in captivity. There is no information on the propagation of cold water anemones, however, but it may be just like other anemones. Similar to other cold water anemones, they reproduce by fission or external fertilization of egg and sperm. When they spawn, they produce larvae that will float away, and eventually finding a spot to land. They then attach and develop a pedal disk that grows into a new anemone.

  • Ease of Breeding: Moderate

Ailments / Diseases

Christmas Anemones are pretty durable once they settle in. Problems 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. Make sure your lighting and water quality is good, and that the food you are offering is to their liking. Some predators include certain nudibranchs, sea stars, and snails.


The Christmas Anemone is generally unavailable to aquarists through local retailers, though it can sometimes be found online.


Featured Image Credit: val lawless, Shutterstock