Introduction to the....
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There are about 30 different species of clown fish that have colors ranging from yellow, orange, black, white, and maroon. The most common known species, the Amphiprion ocellaris are the bright orange clown fish with the white stripes that are popularly found in pet shops all over the world and more famously known for their appearance in the movie, "Finding Nemo." The name "clown fish" originated from the bright colors the fish possesses and its upbeat and bouncy tendencies it has in the water. The fish is constantly dashing, ducking, and darting. Mistakenly, many people assume that clown fish are not aggressive because they are only approximately 13 centimeters in size. Clown fish are extremely territorial and fearless fish and are notorious for biting scuba divers who get too close to their colonies. Clown fish have been known to attack organisms that are more than 1000 times their size! (Clown fish, Bristol Zoo, 1).

The clown fish are acclimated to tropical waters within the Red Sea and Pacific and Indian Oceans. Especially wherever there are corals and sea anemones. The map below shows in red, the areas where the clown fish are commonly found (Clown fish biology, 9):
Clown fish eat algae, zooplankton, crustaceans, and mollusks which make them omnivores! (Shinde, 6).

Protandrous hermaphroditism:
One of the most fascinating facts about the clown fish is its ability to switch sexes. This is known as Protandrous hermaphroditism. Although very little is known about this topic, it is nevertheless fascinating to biologists. Within a colony there is a hierarchy: The largest fish in the colony is the mature female. Interestingly, there is only one female clown fish in each colony and the rest of the colony is made up of juvenile males. The next highest in power is the most mature male clown fish which is the partner of the female clown fish. As a team, the alpha male and the largest female make sure the other male residents stay relatively small. When the female dies, the alpha male switches sexes from male to female and morphs in order to maintain the colony. At this point, the next largest male in the colony takes on the role of alpha male and becomes the partner to the newly morphed female (Clown Anemonefish, 11).

Other fun facts:
  • In the wild these fish can live 6 to 8 years! In captivity they only live 3 to 5 years!
  • Clown fish lay up to 1,000 eggs at a time and all 1,000 eggs survive! This is very uncommon among other fish species!
  • The eggs hatch 7 days after they are laid, the male fish tend to the eggs for all 7 days, fanning them repeatedly so that fungus does not grow on them!
  • Clown fish only lay their eggs during a full moon and the eggs only hatch after dusk (Fun clown fish facts, 10).
  • Overall clown fish are poor swimmers! Who would have guessed that there are poor swimmers in the ocean!?
  • The biggest predator to clown fish are humans. (Shinde,6).

Introduction to the sea anemone:
("The flowers of the sea")
National Geographic: purple sea anemone with its venom filled tentacles awaiting on passing prey.
Sea anemones are long lived, radial shaped organisms without a skeleton. They are closely related to the jellyfish and the coral, as they are within the Cnidarian phylum. There are approximately 1,000 different species of sea anemones throughout the oceans, although most prefer warm tropical waters. The sea anemones are found in every color imaginable. Most frequently sea anemones attach themselves to corals and rocks on the sea floor, although some have the ability of moving 3-4 inches within one hour (Sea anemones, 8). Others have the ability to let themselves be free of their substrates and float around in the water column, followed closely by its anemone fish partners. Although these organisms appear beautiful and are tempting to touch, they are NOT flowers. Sea anemones have stinging cells called nematocysts, which make them extremely dangerous predators (National Geographic, Sea Anemone, 5).

Sea anemones reproduce two different ways. First they can reproduce through lateral fission which is also called budding. Lateral fission/budding is when a clone of the same organism grows out of the organism's side. This baby sea anemone detaches itself from its parent when it is mature enough.They can also reproduce by sexual reproduction when the sea anemone releases egg and sperm and larvae is created and are free living in the water column (Sea Anemones, 8).

The life cycle for the sea anemone is different than others in the Cnidarian phylum considering the sea anemone does not go through a medusoid. Sea anemones start off being fertilized eggs which turn into planula larvae. This larvae develops in the open ocean into a juvenile sea anemone. The juvenile sea anemone is free swimming and does not have tentacles. Eventually the juvenile will settle on a substrate and begin developing tentacles. Once the tentacles are fully developed, the sea anemone has reached the adult stage.The sea anemones are hermaphrodidic which means that they produce both egg and sperm. (University of Alaska Southeast,7).

Life cycle of the sea anemone.

Sea anemones eat fish, mussels, zooplankton, shrimp, and worms through the use of their stinging tentacles. The sea anemone only has one opening...its mouth! Ingestion and excretion is both down by the mouth.

The sea anemone is an opportunistic feeder which means it does not seek out its prey, but rather it waits for its prey to come to it. Sea anemones kill their prey with an organelle they have called a nematocyst. The nematocysts are ejected at the slightest touch upon the sea anemone. The anemone's tentacles fire a filament which injects a neurotoxin into its prey. Some nematocysts pierce straight through the prey, while others wrap around the prey.The neurotoxin causes the prey to become paralyzed which allow the sea anemone to easily move the prey from its ring of tentacles into its gastrovascular cavity.

Fun facts:
*If a sea anemone is torn apart, the pieces can become separate sea anemones.
*Some sea anemones are no more than 0.5 inches, while others can be as large as 6 feet!
*The average lifespan of the sea anemone is 50 years (Sea anemones, 5).
*Some sea anemones have 10 tentacles, while others have hundreds!

Mutualistic symbiosis between the clown fish and the sea anemone:

In Greek the word symbiosis means, "A life together..." (Marine Discovery Lesson,4)

The clown fish and the sea anemone have a mutual relationship with one another: the sea anemone gets food and maintenance from the clown fish and the clown fish gets protection from the sea anemone. The clown fish are known for helping to keep the sea anemones clean by eating the sea anemone's dead leftovers, by eating dead tentacles the sea anemone has lost, and by eating the sea anemone free from parasites. In other words, the clown fish are the "maids" of the sea anemones. Clown fish also provide the sea anemone with its excrement which makes up a large portion of the sea anemone diet alone. Also, the clown fish aid the sea anemone by using their bright colored gills to lure fish and other organisms into the sea anemone so the anemone can capture the lured prey. Finally, the sea anemones profit from the clown fish by getting better water circulation throughout their whole body because the clown fish are constantly swimming throughout their tentacles. At the same time, the sea anemone provides the clown fish with protection against predators using its stinging tentacles. The sea anemone also provides the clown fish with a substrate in which the clown fish can lay their eggs and be protected (Fun Clown fish facts, 10).

Who needs each other more?! :
I think that the clown fish are obligate mutualists of sea anemones, while sea anemones are faculative mutualists with clown fish. What I mean by this is that the clown fish cannot live without the host sea anemone, while the sea anemone can live without the clown fish (Diving with clown fish, 2).(This only applies when the organisms are living in the wild) This relationship is so vital for the clown fish, that it has been witnessed that when a sea anemone relocates, the clown fish move with it. It is very rare that a clown fish will ever venture more than 2 meters away from the host sea anemone, highlighting the strong and necessary symbiosis they share.

How do the clown fish not get stung by the sea anemone?! :
Clown fish are able to interact with toxic sea anemones because they coat themselves in their own slimy mucus. This mucus gives the clown fish immunity from the stinging toxic cells of the sea anemone because the sea anemone mistakes the clown fish for a part of itself. It is believed that the clown fish mucus membrane is based with sugars rather than protein which inhibits the nematocysts from firing. Interestingly, if the clown fish loses the mucus that is on their surface, the tentacles will sting the clown fish and most likely kill them. On the other hand, juvenile clown fish that have not yet created a mucus membrane on themselves are still somehow immune from the stinging cells of the sea anemone which proves that the sea anemone can detect the clown fish in another way other than by the mucus alone. It is also predicted that the clown fish do not get stung by the sea anemone because they build up their immunity. Some scientists believe the clown fish touches one or two of the sea anemone tentacles at a time until it builds immunity and secretes a protective mucus. This would explain why clown fish are immune to their specific sea anemone but not all sea anemones. Unfortunately, scientists do not have an absolute answer to this phenomenon and further studies must be done (Marine Discovery Lesson, 4).

Notice how the clown fish just lays in the middle of the sea anemone full of stinging tentacles without a care in the world!

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external image clown-fish-underwater-photography-15.jpg

Symbiosis Fun Facts:
  • There are about 27 different types of anemone fish and each anemone fish prefers a certain type of sea anemone!
  • Within the sea anemone, the clown fish prefer to sleep near the anemone's oral disk!
  • Sea anemones with anemone fish grow 3x faster than anemones without them!
  • Asexual reproduction by the sea anemone increases with the presence of an anemone fish.


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3. Float video: Uploaded by hotsaltwaterfish on Jul 18, 2010 You Tube

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