Sunflower starfish (Pycnopodia helianthoides)

Sunflower Starfish (Pycnopodia Helianthoides) | A Detailed Guide to Care, Diet and Habitat

The Pycnopodia Helianthoides, Sunflower Sea Star, Sunflower Starfish, or Banded Brittle Star, are some of the largest sea stars. Sunflower sea stars are a popular choice among aquarium residents and marine aquarists. They are readily available, relatively affordable, and easy to care for in most aquariums.

Sunflower sea stars are fairly large sea stars found across the oceans. The scientific name of the sunflower starfish is Pycnopodia helianthoides. This is the only species within its genus, but there are many species of sea star in the Asteroidea class and the Echinodermata phylum.

The common name for the sunflower sea star is the sunflower sea star. They get their name from the distinctive yellow petals of their five arms, arranged like a sunflower. They are closely related to starfish and share many similar traits but also have their own unique characteristics that make them stick out from their cousins.

Appearance and Colour Range

The sunflower sea star is perhaps the most beautiful of all sea stars. The name comes from the many arms, which resemble a flower with petals.

This starfish has a very distinctive appearance and it is among the largest of all sea stars found in the world’s oceans. The average diameter of this animal is around 1 meter (3 feet), but it can grow much larger than that if conditions are right.

As you might expect from an animal of such a large size, this species of sea star requires a large tank and is not suitable for smaller aquariums. The upper side of the sunflower sea star is covered with spines, which are actually small (1mm) pedicellariae. Pedicellariae are pincer-like structures that can clamp onto prey, or protect the body from predators and parasites. The underside contains tube feet, which the Sunflower sea star uses for locomotion, respiration, and feeding.

The color of sunflower sea stars can range from bright orange to deep red, yellow, brown, purple, or even green. The skin is covered in tiny white spines, and the underside of its body can be white, yellow, or orange. Moreover, the mouth is located on the underside of its body, and the color of this species can also change depending on temperature and lighting levels.


The diet of the Sunflower Sea Star consists of sea urchins, clams, Shrimp, Hermit crab meat, squid, oysters, and mussels. These echinoderms use their tube feet to pry shells apart and suck out the animal inside. They have been known to eat other sea stars as well as fish, though this is rare.

It will also eat live rock with dead animals on it as well as algae. It is known to attack other species of starfish in the aquarium, so keep them separate from others. It uses its tube feet to pry its prey open and then extrudes its stomach out of its mouth to fully digest the animal in question. As a result of having such a voracious appetite, it plays a valuable role in keeping the ocean floor clean by eating dead animals and removing parasites from their hosts.

If a meal is too large to eat in one sitting, the sunflower sea star will break it up and store parts of it in its stomach until the meal can be digested.

So the Sunflower Sea Star is a carnivore that typically hunts by extending its arms and then slowly crawling across the ocean floor. It will eat just about any animal it can find, including clams, mussels, barnacles, chitons, snails, sea urchins, sea cucumbers, sand dollars or even other starfish.


The sunflower sea star (Pycnopodia helianthoides) is a large marine invertebrate that lives in the waters off the coasts of Alaska and Canada. Sunflower sea stars were once common in the northeast Pacific from Alaska to southern California and were largest in Puget Sound, British Columbia, northern California, and southern Alaska. They can be found in a variety of habitats, including deep-water and shallow-water rocky reefs, sandy flats, and kelp forests.

Sunflower sea stars are very active hunters that feed on a variety of prey such as mussels, clams, snails, brittle stars, chitons, sea cucumbers, and other echinoderms, including members of their own species.

They sometimes share their tide pool habitat with other species like brittle stars, anemones, and limpets. They are also found in deeper waters further offshore. It is usually found on sandy or rocky bottoms, but can also live in kelp beds and tide pools. When they are young, they are often found in tide pools, but as they grow, they migrate to deeper waters.

Reproduction and Growth of Pycnopodia Helianthoides

Sunflower starfish reproduces sexually and asexually. The sexual reproduction occurs between spring and early summer, while asexual reproduction is exhibited during the rest of the year. During sexual reproduction, males release sperm into the water column which is then taken up by females through their water vascular system and eggs are fertilized internally. The fertilised eggs are brooded in the female’s branchial basket until they hatch as free swimming larvae that undergo direct development to juvenile stage.

Pycnopodia helianthoides, the biggest starfish
Pycnopodia helianthoides, the biggest starfish

Sea stars can also reproduce asexually through fission (splitting in half), where one sea star splits off from its central disc producing two identical animals, fragmentation or by producing offspring from structures called pedicellariae. Sunflower stars also reproduce sexually by releasing eggs and sperm into the water. However, fragmentation is rare in the Sunflower sea star as it has specialised structures called pedicellariae which are able to repair any damage.

Pedicellariae are small jaw-like organs that can remove debris or parasites from the sea star’s body. They have three pincers that can clamp shut and this helps them to clean their bodies and protect themselves from organisms that may attach themselves to the sea star’s skin.

The sunflower star has a slow growth rate. They grow 0.12 to 0.24 inches per month and live for about five years in the wild. This amazing creature can grow up to 60 inches wide and weigh approximately 11 pounds. Their arms look like long spines with tube feet on the end which they use to move along the ocean floor.

Sunflower Sea Star Predators and Threats

Sunflower sea stars have several natural predators and threats. These include:

Fish: Sunflower sea stars eat all kinds of fish, including those who see the sea star as a predator. Some fish find the sunflower sea star intimidating and will not approach it, but others do attempt to eat it. Fish can also munch on the arms of a sunflower sea star if given the opportunity.

Other Sea Stars: Sunflower sea stars can be attacked by other sea stars, even other types of sunflower sea stars. If a larger sunflower sea star is attacking a smaller one, it’s important to separate them immediately before the smaller one is eaten alive.

Parasites: Parasites can attack a sunflower sea star in its habitat, or even while in captivity. If you notice your sunflower sea star has parasites, remove it from its habitat immediately and treat it with an anti-parasite medication as soon as possible.

Birds: Birds are a common predator of the sunflower sea star. Luckily, most birds hunt during the day when the sunflower sea star is not active. This is why it is important to keep your tank covered at all times to avoid unwanted visitors!

Sea otters: Sea otters are another natural predator of the sunflower sea star. They tend to hunt during the day, so make sure your tank is covered at all times.

Climate change and ocean acidification: Climate change and ocean acidification are two threats that could have a major impact on the sunflower sea star population in the future.

Sunflower starfish feeding in their habitat
Sunflower (Pycnopodia helianthoides) sea star

Breeding Guide – What you need to know about breeding Sunflower Sea Star,  Pycnopodia Helianthoides

Tank Requirements and Setup

Tank size

The Pycnopodia Helianthoides is considered a large sea star, reaching a maximum of 30 inches in diameter. This makes it essential to have a tank that is at least 150 gallons or larger (at least 6 feet in length). The larger the tank, the better for this animal.

pH, Temperature, and Salinity

A pH of 8.1-8.4 with an SG reading of 1.025 is optimal for these animals. They prefer water temperatures ranging from 65-72 degrees F, but they can survive in conditions from 55-75 degrees F. These animals do well in tanks with low flow rates with strong water movement above them, such as powerheads or wavemakers.


Sea stars like low lighting conditions and can tolerate almost no lighting at all. This species does not require any special lighting, and will do fine under normal aquarium lights. However, you may need to supplement them with additional food if they are not eating well otherwise.


Waterflow should be gentle to medium around this species as they are more prone to being knocked over in strong currents. If you notice your sunflower sea star struggling to stay upright or clinging onto the glass/rocks during water changes, then make sure you reduce the flow rate as much as possible until it seems more comfortable and stable again!


The substrate in your tank should be fine sand that is easy for your sea star to walk on without getting stuck, as they will often bury their tips underneath it while feeding on live rock and debris in the aquarium. Each arm has hundreds of tube feet that can move small particles of sand off the body, so it is important to have an easy substrate for this species to move about. Be sure that there are many hiding places for your starfish as well, such as live rock structures, so that they can escape from the light if need be. In addition, the bottom of your tank should be dimly lit since the sunflower sea star does not like strong lighting and will often hide from it if given the chance.


A good filtration system is necessary to keep the water quality high. Your sea star will produce a lot of waste, so you will need strong filtration. Filtration for these starfish should be minimal since they feed on the detritus and bacteria that build upon the tank bottom. They only need a powerhead to provide some water circulation.
Make sure to use an air pump that has a flow control valve so you can adjust the flow rate to match your sea stars’ needs (you will want a low flow rate).

Temperament & Aggression

This species is considered peaceful but will eat other invertebrates and small fish if it can catch them. It will also eat shrimp, urchins, and clams. This species is nocturnal and will hide under a live rock and in crevices in the rock work during the day.

Sun starfish are shy and should be kept with other peaceful fish, as they are not aggressive but can be territorial toward their own kind. They are scavengers and will eat just about anything. You must make sure there is always plenty of food in the tank for them to find, or they can starve to death if left alone for too long. They will also pick at the rock work, looking for microscopic food that has fallen from the rockwork into the cracks and crevices in between the rocks. This species is considered peaceful but will eat other invertebrates and small fish if it can catch them. It will also eat shrimp, urchins, and clams.

Compatibility & Tankmates

The sunflower sea star is a peaceful species, so it can be kept with other peaceful species. In the wild, it is found in association with many different invertebrates, such as sponges, anemones, corals, and ascidians.

This species is not reef safe, it will eat all types of invertebrates in the tank. It is recommended to keep only one sunflower sea star per tank. Keep it alone or together with other large sea stars. When kept in captivity, the sunflower sea star is an active predator that will move around and search for food. It has no problem finding food in a well-established aquarium.

You can give this species meaty foods such as clams and mussels, which it will consume quickly. It is also possible to train them to eat thawed frozen shrimp or fish pieces or prepared foods like fortified brine shrimp or mysid shrimp.

So Sunflower sea stars can be kept alone or together with other peaceful species. It is recommended to keep only one Sunflower sea star per tank.

Sunflower Sea Star- Frequently Asked Questions

Q1. Are sunflower sea stars poisonous?

Sea stars are not poisonous, but they are venomous. The difference is that poisonous animals are dangerous to eat or touch, while venomous animals have a mechanism to inject a substance into another animal (usually through a bite or sting). Sea stars can inflict a painful sting with their tube feet, which are covered in venom.

They also have tiny appendages called pedicellariae, which have venom glands and may act as defense mechanisms. However, the degree of toxicity varies between species, so it’s not advisable to handle them without protection.

Q2. What do sunflower sea stars eat?

In the wild, the sunflower sea star has been observed eating bivalves like oysters, mussels, clams, and snails. They prey on mollusks by using their five arms to surround the animal and pull it apart with incredible force. Sunflower stars are carnivores that scavenge for food and hunt for live prey. Their diet consists mainly of urchins, crabs, clams, mussels, and other sea stars.

Q3. Why are sunflower sea stars endangered?

Sunflower sea stars are endangered species due to a recent mass die-off event that has been attributed to a disease known as Sea Star Wasting Syndrome (SSWS). SSWS is characterized by lesions on the surface of the animal, followed by gradual tissue loss and decay. Over time, affected individuals appear to have their bodies melt away before eventually dying. Sunflower sea stars were particularly susceptible to this outbreak due to their tendency to congregate in large numbers on relatively small areas of the coastline.


Sunflower sea stars are a mainly peace-loving species that, despite their appearance, have the personality of a benign and unique pet. The average life expectancy of a sun sea star will depend on water conditions, diet, and other factors that may impact on an individual. The sunflower sea star is easy to care for and rarely suffers from diseases, which makes it the perfect choice for first-time sea star owners. But its low level of aggression also makes it an appropriate choice for more advanced hobbyists who want something interesting and fun to watch.

Sunflower sea stars are remarkable and beautiful animals—particularly when they eat! A great addition to any home aquarium!

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