Top 15 Animals with the Ability to Change Genders in Nature

While most moray eels are born as either males or females and retain their gender throughout their life, a few species are hermaphroditic. For example, the ribbon moray eel, pictured above, can transition from male to female.

The Ribbon Moray, scientifically known as Rhinomuraena quaesita, is a species of marine eel and the sole member of the genus Rhinomuraena. It is native to the Indo-Pacific region and can also be found in the waters off Vietnam.

This elegant creature has a long, slender body and a high dorsal fin. The Ribbon Moray can be easily identified by the large nostrils on its face. Juveniles and young adults swim freely with black bodies and a yellow dorsal fin, while females are yellow with a black anal fin. Mature males are blue with a yellow dorsal fin.

The Ribbon Moray grows to a length of about 1 meter (3.3 feet) and has a lifespan of up to twenty years. It is the only species of moray eel known to have the ability to change gender.

The banana slug, with its distinctive yellow body, can grow up to 25 cm in length. This hermaphroditic creature has both male and female reproductive organs. While it has the ability to self-fertilize, most banana slugs prefer to find a mate for reproduction.

Belonging to the genus Ariolimax, the banana slug comprises three species found in North America. These slugs are usually yellow, with occasional brown spots, resembling a ripe or overripe banana. Although they are typically yellow, they can also appear in green, brown, or white.

Some Ariolimax columbianus individuals may have such extensive black markings that they appear almost entirely black. The color of these slugs can change depending on their diet, exposure to light, and humidity levels.

In some species, such as butterflies, sexual dimorphism is evident across the entire body. Literally, both male and female characteristics—such as colors and traits—are displayed on the same organism. This rare condition is known as gynandromorphism, which results from a genetic mutation during early cell division.

Butterflies are small, flying insects in the order Lepidoptera, known for their colorful, vibrant patterns. They are primarily diurnal and often inhabit areas with abundant flowering plants where they feed on nectar and pollen, contributing to pollination. Butterflies are sometimes casually referred to as 'butterflies' or 'moths,' although moths are a distinct group.

The striking colors of butterfly wings are produced by thousands of tiny scales that overlap. In some cases, pigment grains contribute to the coloration. More commonly, the scales' surfaces refract light, causing the colors to shift and shimmer as the butterfly moves. Typically, the underside of the wings is duller in shades of gray or brown, providing camouflage when the wings are folded, helping the butterfly evade predators like birds and insects.

Some Northern Cardinals display physical traits of both sexes. The bird in the image has one half of its plumage brownish-gray (characteristic of females) and the other half bright red (characteristic of males).

The Northern Cardinal (Cardinalis cardinalis) is a songbird species found in North America, ranging from southern Canada through the eastern United States, from Maine to Texas, and south into Mexico. They typically inhabit woodlands, gardens, shrubs, and wetlands.

This medium-sized bird measures around 21 cm in length and has a distinctive crest on its head. Males have vibrant red feathers with a black mask around their face, while females have more muted, olive-red plumage. Cardinals primarily feed on seeds, but will also eat insects and fruits. Males are territorial and use their songs to mark their boundaries. During courtship, males feed seeds to the females. Their nests usually contain 3-4 eggs. While once a popular pet, the Northern Cardinal has been banned in the U.S. under the Migratory Bird Treaty Act of 1918.

In the wild, an increasing number of male frogs are transforming into fully functional female frogs, complete with reproductive organs. The primary cause of this gender shift is the herbicide atrazine, which accumulates in rivers and lakes, adversely affecting the frogs' sexual development. As a result of this herbicide runoff, many North American male frogs have been unintentionally undergoing sex changes, with some even becoming fully functional females.

Adult frogs, during their breeding season (late spring, after the first summer rains), engage in vocalizations to attract mates. The female carries the male on her back, and the male clings to her abdomen as they travel to the water’s edge to lay eggs. As the female lays her eggs, the male fertilizes them externally. Fertilization takes place outside the female's body.

Frogs typically live in damp environments near bodies of water (ponds, marshes, etc.), and are nocturnal feeders. Their diet consists of insects, small fish, worms, and snails. Frogs hibernate during the winter months (a phenomenon known as brumation). As cold-blooded animals, frogs have smooth, moist skin, powerful legs, and wide webbed feet. Frogs vary greatly in size, from the small wood frog (Rana sylvatica) to the world's largest frog, the Goliath frog (Conraua goliath).

Most frog species are aquatic or semi-aquatic, laying their eggs in water and undergoing a tadpole stage. However, some species are arboreal, and a few can even survive in brackish water.

Some female snakes, such as the cottonmouth (Agkistrodon piscivorus), have the remarkable ability to self-fertilize their eggs without the need for a male. This means these snakes can perform the reproductive functions of both sexes simultaneously.

Cottonmouths are typically found in the southeastern United States, particularly in areas like South Carolina and Florida. These snakes are commonly seen near freshwater habitats such as rivers, lakes, ponds, and swamps, and interestingly, they also inhabit drainage ditches. They are mostly nocturnal, spending the day sunbathing to regulate their body temperature, and they tend not to attack unless provoked or hungry.

Their diet consists of both warm-blooded and cold-blooded animals, including fish, frogs, rodents, salamanders, lizards, baby turtles, young alligators, birds, small mammals, and even other snakes. Hatchlings have a unique hunting method where they gently wiggle the tip of their tail to mimic a worm or insect, luring prey close enough to strike.

This species is currently under threat due to habitat loss and has been listed as near-threatened on the IUCN Red List since 2010.

The bearded dragon (Pogona), native to Australia, has the remarkable ability to change its sex during the incubation process. Research shows that when eggs are incubated at warmer temperatures, male bearded dragons often transform into females.

Pogona is a genus of reptiles in the Agamidae family, consisting of six species commonly referred to as bearded dragons. These lizards have a semi-arboreal lifestyle, spending time both in trees and on the ground, although they are often found in bushes and close to human settlements.

Bearded dragons sunbathe on exposed rocks and tree branches during the mornings and afternoons to regulate their body temperature. Their diet mainly consists of insects, plants, and occasionally small rodents. They are found throughout Australia and inhabit a wide range of environments, including deserts, scrublands, and eucalyptus forests.

Spotted hyenas are notoriously difficult to distinguish between males and females, as both sexes share the same body size and shape. Interestingly, both have similar genitalia, with females possessing an erect pseudo-penis when in the presence of close relatives.

As the largest member of the hyena family, the spotted hyena measures between 95–165 cm in length, stands about 70–90 cm tall, and weighs between 50–70 kg. They stand out physically from other hyena species with a bear-like build, rounder ears, less prominent manes, spotted fur, multipurpose teeth, fewer nipples, and the presence of a pseudo-penis in females. They are also the only mammals without an external vaginal opening.

Spotted hyenas can adapt to various environments, ranging from dry, hot lowlands in the north and south of their range to the cold, mountainous terrains of East Africa and Ethiopia. They often coexist with human settlements.

Most famous for their signature cackling laughter-like sound, spotted hyenas are often mischaracterized as scavengers, though they are formidable hunters. Their diet primarily consists of live prey, rather than carrion.

The Marsh Harrier is a remarkable bird of prey, part of the hawk family, and known for its impressive size and hunting abilities. Its powerful wings allow it to soar high in the sky while searching for prey. Primarily found in Europe, these birds thrive in marshland environments. Let's explore their key features.

These birds are often described as formidable and predatory, with a robust and menacing appearance. They stand upright, with straight backs and necks. When in flight, they tilt their heads downward to scan for potential prey.

With a sharp, curved beak and strong jaws, the Marsh Harrier is well-equipped to tear into its prey. The upper beak is covered with a thick, yellowish membrane known as the cere. Their large, tube-shaped eyes provide extraordinary vision—up to eight times sharper than humans—which helps them spot even the smallest prey from great heights. In addition to their excellent vision, many species also have exceptional hearing, which aids in detecting prey hiding in dense vegetation.

Marsh Harriers have long, wide wingspans, ranging from 1.6 meters to over 3 meters, allowing them to fly at high speeds and perform dramatic dives to catch prey, reaching speeds of up to 300 km/h.

The Bluegill Sunfish comes in three distinct types: the spawning type, the satellite type, and the ‘tennis shoe’ type. The spawning type builds nests and attracts females, while the satellite type mimics females but is actually male and can release sperm. The tennis shoe type, the smallest, is a male that disguises itself as a juvenile fish.

This species, a freshwater fish in the sunfish family, is native to North America and can be found in rivers, lakes, streams, and ponds. It's a popular sport fish and also an invasive species. The Bluegill is the state fish of Illinois.

Bluegills can grow up to 12 inches (30 cm) long and weigh around 4.5 pounds, with an average size of about 8 inches (20 cm). Their dark-colored bodies are covered with blue spots, and their bellies feature a pale orange or yellow hue. Their sharp, rigid dorsal fins and black gill covers resemble those of tilapia. These fish are omnivorous, preying on smaller fish and even other Bluegills. Though edible, their flesh is not particularly tasty. Bluegills are prolific breeders, making them easy to farm.

Despite their carnivorous diet, Bluegills are also preyed upon by larger fish such as pike, catfish, and bass, which can easily snap up a 20 cm Bluegill. These fish have relatively poor vision, making it difficult for them to spot prey from a distance. They are opportunistic feeders, often attacking smaller fish and tend to stay still unless hunting. During spring, common bait for catching Bluegills includes live worms, small amphibians, crickets, and small leeches, as they are expert at devouring these.

The Red Colobus and Olive Colobus monkeys are Old World monkeys that live in male-dominated groups. Once males reach maturity, they are often driven out of the group. However, some males experience an unusual phase where their genitalia resemble females, even though they are still male.

The Red Colobus is an Old World monkey in the genus Piliocolobus, closely related to the Black-and-white Colobus (genus Colobus). The East African Red Colobus is often preyed upon by common chimpanzees. These monkeys are found in the tropical rainforests of West, Central, and East Africa, with the Zanzibar Red Colobus living in coastal bushland. Due to habitat loss and hunting, most subspecies of the Red Colobus are classified as endangered or critically endangered by the IUCN, making them one of the top 25 most at-risk primate species in the world.

The Olive Colobus lives in groups ranging from 15 to 150 members, with a few males, many females, and their young. Each member holds a rank within the group. One of the key reasons for their success is their omnivorous diet. Like other baboons, they will eat virtually anything, allowing them to find nutrients in almost any environment and adapt to various foraging strategies.

The Giant Australian Cuttlefish is a fascinating creature, known for its enormous brain shaped like a donut. This species has highly developed eyes designed to detect and evade predators. The ratio of male to female cuttlefish is typically 11:1, which leads to fierce competition among males for mating rights. To avoid detection while crossing into the territories of other males, some males mimic the coloring of females.

Sepia apama, or the Giant Australian Cuttlefish, is a type of cuttlefish known for its large body, reaching a mantle length of 50 cm (20 inches) and weighing over 10.5 kg. It is native to the southern coast of Australia, ranging from Brisbane in Queensland to Shark Bay in Western Australia. These cuttlefish are commonly found around rocky reefs, seagrass beds, and sandy or muddy bottoms, typically at depths up to 100 meters.

Clownfish are brightly colored, with orange bodies marked by three white stripes. They are hermaphrodites, meaning they can reproduce as both males and females, although they do not produce both eggs and sperm at the same time. Born as one gender, clownfish can change their sex if needed to ensure the survival of their group.

Also known as anemonefish, clownfish (Latin: Amphiprioninae) are marine species that inhabit coral reefs and rocky shorelines. Within the family Pomacentridae, about 30 species have been identified, with some belonging to the genus Premnas and others to Amphiprion. In the wild, clownfish often live in symbiotic relationships with sea anemones. Depending on the species, they may appear in colors ranging from yellow and orange to light red or black, with contrasting white stripes. The largest clownfish can reach lengths of 18 cm (7.1 in), while the smallest species are only around 10 cm (3.9 in).

Clownfish are omnivores, feeding on various types of food, including undigested material from their sea anemone hosts. Their waste provides nutrients for the anemones. They mainly consume planktonic animals such as copepods and larval shrimp, though some species also feed on algae. Clownfish communicate by creating a series of rapid clicking sounds by snapping their jaws together. This is usually done when they sense a territorial threat or when seeking a mate. They produce up to five clicks per second, but how they make this sound remains a mystery.

Jawfish live in groups, but only one male exists within each group, and it is always the largest. If the male dies or disappears, one of the females will transform into a male to take its place.

Interestingly, these male jawfish, which typically grow to no more than 15 cm, have the unique task of nurturing up to 400 eggs in their mouths. To keep the eggs supplied with oxygenated water, the male must continuously open and close its mouth. The reproductive process of jawfish is quite fascinating. After the female lays hundreds of eggs in the male's mouth, the male carries them until they hatch.

During this incubation period, the male jawfish cannot leave its burrow to feed and must survive on plankton that drifts into its mouth. After fertilizing the eggs, the male ensures their safety in his mouth until they hatch. The entire process causes the male to lose weight, as it cannot eat, but once the eggs hatch, the male finally has a chance to recover and feed.

Male bass found across rivers in the southeastern United States often exhibit female-like traits. Studies show that between 70-90% of male bass in this region are hermaphrodites, possessing immature eggs that develop within their testes.

The term 'bass' refers to several species of fish, both freshwater and marine, all belonging to the larger Perciformes order. While bass share many similarities with the sunfish, the term 'bass' historically referred to the sunfish in Old English.

Known for their economic value, bass are prized for their nutritional benefits and are farmed in both saltwater and freshwater environments. They are popular targets for recreational and sport fishing, especially in North America, where species like the black bass are particularly well-known.

Bass are characterized by their long bodies, wide mouths, and asymmetrical jaws, with the upper jaw extending behind the eyes. Their heads are pointed, and their dorsal fins are distinctly shaped with a concave upper contour. Some bass species can grow to impressive sizes, reaching lengths of up to 2 meters and weighing up to 60 kg.

Many bass species are capable of reaching massive sizes, with some individuals exceeding 50 kg or even 70 kg. For instance, a bass weighing 112 kg and measuring over 1.8 meters was caught in Uganda. The current world record for bass weight is held by a 10 kg fish, while a bass weighing 16.89 kg was recorded in Vietnam's Huong River, setting a new record for the region.