Do you still remember Nemo, the clownfish from the Disney animated film "Finding Nemo"? Despite the "clown" in their name, clownfish are quite beautiful.

They are named after the white stripes on their heads, resembling the makeup of a clown in traditional theater, hence the name.

Clownfish are tropical marine fish found in the Indian and Pacific Oceans, including areas around Japan, Australia, and the Indo-Pacific region.

Clownfish are small in size, typically reaching lengths of only around 11 centimeters. They have distinctive features such as white patches on their foreheads and sides, with their dorsal and anal fins mostly black except for the transparent rays of their pectoral and soft dorsal fins. Juvenile clownfish have black scales with blue accents, while adults are primarily bright red with black-rimmed white stripes behind their eyes.

These fish are commonly found inhabiting coral reefs and rocky outcrops. During their juvenile stage, they often form symbiotic relationships with sea anemones, sea urchins, and others.

Sea anemones' tentacles secrete venom, but clownfish have a special mucus on their skin that protects them from toxins, allowing them to coexist safely within the anemones. Protected by the anemones, clownfish avoid attacks from larger fish and utilize the anemones' tentacles for nesting and spawning.

They also help to "clean" food debris from the anemones and scavenge leftovers, while their presence attracts other fish to the anemone, providing hunting opportunities for the anemone. Additionally, clownfish aid in removing necrotic tissue and parasites from the anemones, establishing a mutually beneficial symbiotic relationship termed "mutualism" in biology.

One remarkable characteristic of clownfish is their ability to change gender. In every clownfish group, there is a dominant female. If the dominant female dies or disappears, her mate, the male, undergoes hormonal changes and transforms into a female within a few weeks, acquiring all the physiological functions of a female.

Subsequently, it gradually changes its external features, such as body size and coloration. The new female then selects the strongest male as a mate to continue breeding. However, it's worth noting that clownfish can only change from male to female and not vice versa.

Clownfish also exhibit strong territorial behavior. Typically, a mated pair of clownfish occupies a single sea anemone, excluding other conspecifics. Even in large anemones, they allow only a few juveniles to enter. Within this family unit, the dominant female and her mate assert dominance, often suppressing other clownfish and driving them into the corners of the anemone to defend their territory.

Thus, clownfish are far from being simple creatures solely judged by their appearance. With their unique survival skills, they carve out their niche in the vast oceans.