Sirenians: Characteristics, Classification, Evolution, and Diversity

Introduction

Sirenians are a group of fully aquatic, herbivorous mammals commonly known as sea cows. Belonging to the order Sirenia, these unusual animals include manatees and dugongs, which inhabit tropical and subtropical marine, coastal, and freshwater environments. Although they spend their entire lives in water, they breathe air, give birth to live young, and feed their offspring with milk.

Sirenians are among the few living mammals that depend mainly on aquatic plants for food. Their bodies have evolved several specialized features for underwater life, including paddle-shaped forelimbs, powerful tails, reduced hind limbs, and flexible upper lips that help them collect vegetation. Consequently, they can feed efficiently in seagrass meadows, rivers, estuaries, and shallow coastal waters.

The evolutionary history of Sirenia extends back more than 50 million years. Fossils reveal how early members gradually transformed from four-legged terrestrial or semi-aquatic mammals into fully aquatic animals. Furthermore, their evolutionary relationships connect them with elephants and other members of the mammalian group Afrotheria.

Today, four living sirenian species survive: three manatees and one dugong. However, their populations face serious challenges, including habitat degradation, boat collisions, fishing activities, pollution, and other human pressures.

This article explores the characteristics, anatomy, evolutionary history, classification, living and extinct species, habitats, ecological roles, and conservation of sirenians.

What Are Sirenians?

Sirenians are large, plant-eating aquatic mammals that belong to the order Sirenia. People commonly call them sea cows because they consume aquatic vegetation and spend much of their time grazing underwater.

The order contains two families with living representatives: Trichechidae, which includes manatees, and Dugongidae, which includes the dugong. A third family, Hydrodamalidae, contained several extinct relatives, including the enormous Steller's sea cow.

Unlike dolphins and whales, which belong to the order Cetacea, sirenians primarily eat aquatic plants. They spend much of their time searching for and consuming vegetation, particularly seagrasses and freshwater plants.

Their bodies support slow, controlled movement through water. They generally have thick bodies, small eyes, movable lips, and forelimbs modified into flippers. Although modern sirenians lack external hind limbs, they retain small remnants of the pelvic skeleton inside their bodies.

Sirenians must regularly surface to breathe because they have lungs rather than gills. Therefore, they cannot obtain oxygen directly from water, even when they spend long periods underwater feeding or travelling.

Most living species prefer warm-water environments. Manatees inhabit freshwater, brackish water, and marine habitats, whereas dugongs live mainly in coastal marine waters and depend heavily on seagrass ecosystems.

The four living species are:

• West Indian manatee (Trichechus manatus)
• Amazonian manatee (Trichechus inunguis)
• African manatee (Trichechus senegalensis)
• Dugong (Dugong dugon)

Although these animals share a common evolutionary background, they differ in geographical distribution, tail shape, skull structure, and feeding adaptations. These differences help scientists distinguish the two living families.

Origin and Evolutionary History of Sirenians

The evolutionary history of sirenians began during the early Cenozoic Era, approximately 50 million years ago. Their earliest known relatives lived in ancient coastal environments and retained several features that helped them move on land.

Sirenians belong to Afrotheria, a major evolutionary group of mammals that also includes elephants, hyraxes, aardvarks, elephant shrews, and tenrecs. Molecular studies and anatomical comparisons support these relationships.

Within Afrotheria, sirenians belong to the broader evolutionary group Paenungulata, which also includes elephants and hyraxes. Sirenians share a particularly important evolutionary association with elephants and their extinct relatives through the group Tethytheria.

Early sirenian ancestors had four functional limbs and could move on land. Nevertheless, their association with aquatic environments encouraged gradual changes in their bodies. Over millions of years, natural selection favored features that improved swimming and underwater feeding.

Several major anatomical transformations occurred during this transition:

• The hind limbs gradually became smaller and eventually disappeared externally.
• The forelimbs developed into flippers that helped with steering and balance.
• The tail became an increasingly important source of swimming power.
• The body developed a shape better suited to aquatic movement.
• In several lineages, the skeleton developed increased bone density.
• The skull and teeth became increasingly specialized for consuming aquatic vegetation.

As these changes accumulated, early sirenians became more dependent on water. Later forms developed fully aquatic bodies and lost the ability to walk on land.

Different evolutionary lineages also explored different feeding strategies and habitats. Some ancient forms retained relatively generalized characteristics, whereas others developed adaptations for grazing on seagrasses.

Therefore, sirenian evolution did not involve one sudden transformation. Instead, it involved a long series of anatomical and ecological changes that gradually produced the modern manatees and dugongs.

Their history demonstrates how terrestrial mammals can become highly specialized aquatic animals while retaining the basic biological characteristics of mammals.

Classification and Evolutionary Relationships of Sirenians

Sirenians belong to the order Sirenia within the class Mammalia. They are placental mammals and members of the Afrotheria evolutionary group.

Their classification includes both living species and numerous extinct relatives known from fossils.

A simplified taxonomic arrangement is:

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Infraclass: Placentalia
• Superorder: Afrotheria
• Order: Sirenia

The living order contains two families.

Family Trichechidae

This family includes manatees. All three living species belong to the genus Trichechus.

Family Dugongidae

This family includes the living dugong and several extinct relatives. The dugong (Dugong dugon) is its only surviving species today.

Dugongidae also included extinct animals such as Hydrodamalis gigas, the Steller's sea cow, which belonged to the subfamily Hydrodamalinae.

Other extinct sirenian lineages, including the family Protosirenidae, provide evidence of the early diversification of the order. Scientists continue to investigate the precise evolutionary relationships among these fossil groups.

Sirenians share Afrotherian ancestry with elephants and hyraxes. More specifically, their evolutionary history places them within Paenungulata, alongside these relatives.

However, sirenians are not close relatives of seals, sea lions, or whales simply because they share aquatic habitats. These mammals belong to different evolutionary lineages.

Modern classification therefore reflects common ancestry rather than superficial similarities in body shape or lifestyle.

Geological Timeline and Fossil Record of Sirenians

The fossil record provides valuable evidence of the transformation from four-limbed early sirenians into fully aquatic mammals. Paleontologists have discovered sirenian fossils in North America, Europe, Africa, Asia, and other regions that once contained suitable coastal environments.

The earliest widely recognized sirenians appeared during the early Eocene Epoch, approximately 50 million years ago.

Early Eocene: The first known sirenians

Some of the oldest recognized sirenians include Prorastomus and Pezosiren. These animals retained functional limbs and several skeletal features associated with terrestrial or amphibious movement. Pezosiren portelli, discovered in Jamaica, is particularly important because its skeleton combines terrestrial and aquatic characteristics. It had four functional limbs, a strong pelvis, and skeletal features that indicate an increasingly aquatic lifestyle.

Middle Eocene: Increasing aquatic specialization

During the middle Eocene, more specialized sirenians appeared. For example, Protosiren possessed anatomical features associated with a more aquatic lifestyle, although researchers continue to investigate its exact locomotor abilities. These fossils help scientists trace changes in the limbs, pelvis, and body structure as sirenians adapted to life in water.

Late Eocene and Oligocene: Diversification

Later sirenians developed increasingly specialized aquatic features. Several lineages evolved different feeding structures and stronger swimming adaptations. At the same time, their geographical distribution expanded into different marine environments. These habitats offered aquatic vegetation that supported their herbivorous diets.

Miocene and Pliocene: Major evolutionary changes

During the Miocene and Pliocene epochs, sirenians diversified into several families and genera. Dugongids became particularly important in many marine ecosystems. The fossil record also reveals large extinct relatives of modern dugongs and manatees. One remarkable example is Hydrodamalis gigas, the Steller's sea cow, which survived until historical times.

Quaternary to the present

During the more recent geological past, sirenian diversity declined. Climate changes, habitat shifts, and other environmental pressures influenced the distribution of different lineages.

Human hunting later caused the extinction of Steller's sea cow in the eighteenth century. Its disappearance provides a clear historical example of human-driven extinction among marine mammals.

Fossil bones, teeth, skulls, and limb structures allow scientists to reconstruct these evolutionary changes. Furthermore, the geographical distribution of fossils provides clues about ancient coastlines, marine vegetation, and environmental conditions.

However, the fossil record remains incomplete. Geological processes and preservation conditions do not preserve every animal or evolutionary stage. Consequently, scientists combine fossil evidence with anatomical and molecular research to investigate sirenian relationships.

Defining Characteristics of Sirenians

Sirenians possess several distinctive features that separate them from other aquatic mammals. Although manatees and dugongs differ in appearance, they share important anatomical and physiological characteristics.

Fully aquatic lifestyle: Sirenians spend their entire lives in aquatic environments. Unlike amphibious mammals, they do not normally come onto land to rest, feed, or reproduce.

Herbivorous diet: They feed mainly on aquatic plants. Seagrasses play a particularly important role in the dugong's diet, while manatees consume a broader variety of marine and freshwater vegetation.

Paddle-shaped forelimbs: Their front limbs form flippers that help them steer, maintain balance, and move vegetation toward the mouth.

Reduced hind limbs: Modern sirenians lack externally visible hind legs. Nevertheless, small vestigial pelvic elements remain inside their bodies.

Powerful tail: The tail provides the main force for swimming. Manatees have rounded tails, whereas dugongs possess forked tail flukes.

Dense skeletal structure: Many sirenians have unusually dense bones. Scientists describe increased bone density as pachyostosis or osteosclerosis, depending on the structural changes involved. These features influence body density and buoyancy.

Air-breathing respiration: Sirenians possess lungs and must regularly surface to breathe.

Specialized lips and teeth: Their flexible upper lips help them collect vegetation, while their teeth process tough plant material.

Mammalian reproduction: Females give birth to live young and nourish their calves with milk produced by mammary glands.

Warm-water preference: Most living species inhabit tropical and subtropical waters. However, some populations tolerate seasonal temperature changes and use warmer areas during colder periods.

Sirenians also have relatively low metabolic rates compared with many other mammals of similar size. This characteristic relates to their slow-moving lifestyle and the relatively low energy content of much aquatic vegetation.

Together, these features make sirenians highly specialized aquatic herbivores. Their anatomy and physiology allow them to occupy an ecological role that few other living mammals share.

Skeletal System and Aquatic Adaptations

The sirenian skeleton has undergone substantial modifications as their ancestors adapted to life in water. These changes support swimming, buoyancy control, feeding, and the protection of internal organs.

The skull contains specialized structures associated with herbivorous feeding. Differences in jaw arrangement and tooth structure also help distinguish manatees from dugongs.

The vertebral column supports the trunk and connects with the tail region. In addition, vertebrae and associated muscles allow the body to move during swimming.

One of the most unusual features of sirenian anatomy is their dense skeleton. Many species possess heavy ribs and other bones that contribute to overall body density. As a result, these animals can counteract buoyancy and remain submerged more easily while grazing.

Their forelimb skeleton has changed into a flipper. Inside each flipper, scientists can identify modified mammalian limb elements, although their shapes and proportions differ considerably from those of terrestrial relatives.

The pelvic bones have become greatly reduced. Modern sirenians no longer have functional external hind limbs, unlike their early fossil relatives, which retained four legs.

Meanwhile, powerful muscles around the tail generate the force needed for forward movement. Manatees use a broad, rounded tail, whereas dugongs swim with a forked fluke.

These skeletal modifications illustrate how evolution can reshape the mammalian body to meet the demands of a completely aquatic lifestyle.

Feeding Mechanisms and Herbivorous Diet

Sirenians are specialized aquatic herbivores. Their diet consists mainly of submerged, floating, or shoreline vegetation, although food preferences vary between species and habitats. Dugongs depend heavily on seagrass meadows. They commonly feed on seagrass growing in shallow coastal waters, using their downward-facing snouts to crop or uproot vegetation from the seabed.

Manatees have a broader diet. Depending on their species and location, they consume seagrasses, freshwater plants, floating vegetation, and aquatic leaves.

Feeding adaptations

The flexible upper lip plays an important role in food collection. Manatees use their divided, muscular upper lip to grasp, manipulate, and bring vegetation toward the mouth.

Dugongs, on the other hand, use their specialized snouts to dig through sediment and collect seagrass. Their feeding activity can leave visible trails across seagrass beds.

Teeth and food processing

Manatees have continuously replacing molars. As older teeth wear down, new teeth develop toward the back of the jaw and gradually move forward. Scientists sometimes call this process marching molar replacement.

Dugongs have a different dental arrangement. Adult males may develop small tusk-like upper incisors that become more visible as they mature. However, these tusks do not perform the same grinding function as the molars. Both groups use their teeth to process tough plant material, although their feeding methods and dental structures differ.

Digestive system

Like other herbivorous mammals, sirenians have digestive systems adapted to extract nutrients from plant material. Their long digestive tracts support microbial fermentation, which helps break down fibrous vegetation.

The large intestine plays an important role in digestion and water absorption. Furthermore, food processing takes considerable time because aquatic plants often contain large amounts of fibre and relatively little energy.

Their feeding activity also influences aquatic habitats. By consuming vegetation, sirenians affect plant growth, nutrient cycling, and the structure of underwater ecosystems.

External Anatomy and Body Structure

The external body of a sirenian is generally large, rounded, and elongated. This shape helps the animal move through water while allowing it to reach and consume aquatic vegetation.

Scientists describe the body in terms of the head, trunk, and tail region. However, these divisions appear less distinct than they do in many terrestrial mammals.

Head and muzzle

The head is relatively small compared with the body. The muzzle is broad and flexible, particularly in manatees, which use their upper lips to collect and manipulate vegetation.

Dugongs have a more downward-facing snout. This shape helps them graze on seagrass growing along the seabed. Consequently, their muzzle structure closely reflects their feeding behavior.

The nostrils sit near the upper surface of the snout. Muscular valves close them when the animal dives, helping prevent water from entering the respiratory passages.

Eyes and ears

Sirenians have relatively small eyes, but they can see underwater. They also have small external ear openings without prominent external ears.

Forelimbs

Their forelimbs form paddle-shaped flippers. These structures help the animals steer, control their position, and move vegetation toward the mouth. Manatees can also use their flippers to hold food or assist with movement along the bottom. The range of movement varies between species.

Tail

The tail provides one of the clearest external differences between manatees and dugongs. Manatees have broad, rounded, paddle-shaped tails. In contrast, dugongs possess a forked tail fluke that resembles the tails of dolphins and whales. Both groups generate propulsion through vertical tail movements.

Skin

Sirenians have thick, rough skin with relatively little hair. However, specialized sensory hairs, especially around the muzzle, help them detect and handle food.

Overall, their external body structure reflects their specialized aquatic lifestyle. Each major feature contributes to swimming, feeding, or sensing the surrounding environment.

Respiratory and Circulatory Systems

Sirenians are mammals, so they breathe atmospheric oxygen through lungs. They cannot extract enough oxygen directly from water. Therefore, they must periodically rise to the surface. Their nostrils sit near the upper surface of the snout, allowing them to breathe without lifting the entire head out of the water. Muscular valves close the nostrils when the animal submerges.

Their lungs are elongated and lie along much of the back region of the body. This arrangement relates to their unusual body shape and helps them maintain a stable position while swimming. Sirenians can remain underwater for several minutes, depending on their activity level and physiological condition. When resting, they may stay submerged longer than when actively swimming or feeding.

Circulatory system

The circulatory system follows the basic mammalian pattern. It includes a four-chambered heart, blood vessels, and blood that transports oxygen and nutrients throughout the body. The heart pumps oxygen-poor blood toward the lungs, where gas exchange takes place. Oxygen-rich blood then returns to the heart, which pumps it throughout the body.

Their relatively low metabolic rate supports their slow-moving lifestyle and plant-based diet. Nevertheless, they still need an efficient circulatory system to supply oxygen to tissues and support swimming, digestion, growth, and reproduction.

Temperature regulation

Sirenians prefer warm aquatic environments. Unlike many other marine mammals, they have limited insulation, so prolonged exposure to cold water can threaten their health.

Some populations use warm-water refuges during colder periods. For example, West Indian manatees may gather near natural warm springs during winter. In some regions, they also use warm-water discharges from power plants.

These respiratory, circulatory, and temperature-related adaptations help sirenians survive in aquatic environments while maintaining the essential physiological functions of mammals.

Nervous System and Sensory Abilities

The nervous system coordinates movement, feeding, communication, and responses to the surrounding environment. Like other mammals, sirenians possess a brain, spinal cord, and network of peripheral nerves.

Their senses help them navigate underwater environments, where light, sound, and chemical signals behave differently from those in terrestrial habitats.

Vision

Sirenians have relatively small eyes, but they can see underwater. Their vision helps them detect objects, recognize environmental features, and respond to nearby animals.

Hearing

Hearing helps sirenians detect sounds and vibrations underwater. They can perceive aquatic sounds, although they do not use the sophisticated echolocation system found in dolphins and some other toothed whales.

Touch and tactile sensitivity

Touch plays a particularly important role in sirenian behavior. Their muzzles contain numerous sensitive hairs called vibrissae. These structures help them locate, grasp, and manipulate aquatic plants. Manatees also have sensory hairs across parts of their bodies. These hairs may help them detect water movements and physical contact.

Smell and taste

Chemical senses help sirenians recognize food and respond to their environment. However, scientists understand the relative importance of smell and taste less fully than some of their other sensory abilities.

Together, these sensory systems help sirenians navigate shallow water, find food, communicate, and respond to potential threats. Tactile sensitivity is especially valuable because they often feed close to the seabed or among dense vegetation.

Reproduction, Development, and Life Cycle

Sirenians reproduce sexually and give birth to live young. Their reproductive biology follows the basic pattern of other large mammals, although their aquatic lifestyle influences mating, birth, and parental care. Females usually give birth to a single calf after a long gestation period. The exact duration varies between species, but pregnancy commonly lasts around a year or slightly longer.

Mating and fertilization

Sirenians mate in water. In some species, several males may follow a receptive female during a mating period. Their reproductive behavior can include close swimming, physical contact, and repeated mating attempts. Like other mammals, sirenians use internal fertilization.

Birth and early development

Newborn calves are relatively well developed. They can swim shortly after birth and must reach the water surface to breathe. The mother feeds her calf with milk from mammary glands located near the forelimbs. Nursing takes place underwater, allowing the calf to remain close to its mother.

Parental care

Female sirenians provide extended care for their young. Calves remain close to their mothers and follow them during feeding and travel. The mother protects her calf from danger. In addition, repeated exposure to feeding areas and environmental conditions helps the young animal learn where to find food. As the calf grows, it gradually becomes more independent. However, the period of maternal care can last for an extended time.

Growth and maturity

Growth rates vary between species and environmental conditions. Sirenians generally mature slowly and have relatively low reproductive rates compared with many smaller animals. Females may not reproduce every year, particularly when they care for a calf. Consequently, populations can struggle to recover from additional mortality caused by hunting, boat strikes, and habitat loss. Their life history highlights the importance of protecting adult females, breeding habitats, and areas used by young animals.

Major Groups, Living Species, and Extinct Sirenians

Modern Sirenia contains four living species, but the fossil record reveals a much larger diversity of extinct forms. The living species belong to two families: Trichechidae and Dugongidae.

Living manatees

Manatees belong to the family Trichechidae. They generally have rounded tails, flexible upper lips, and a broad diet of aquatic vegetation.

1. West Indian manatee (Trichechus manatus)

The West Indian manatee inhabits the Caribbean region, the Gulf of Mexico, and parts of the Atlantic coast of Central and South America. Scientists commonly recognize two subspecies: the Florida manatee and the Antillean manatee. These animals use coastal waters, estuaries, rivers, and freshwater springs.

2. Amazonian manatee (Trichechus inunguis)

The Amazonian manatee lives in the freshwater systems of the Amazon Basin. It is the smallest living manatee species and has adaptations suited to river and floodplain environments. Its distribution follows seasonal changes in water levels and the availability of aquatic vegetation.

3. African manatee (Trichechus senegalensis)

The African manatee inhabits rivers, lakes, estuaries, and coastal waters across western and central Africa. It consumes a variety of aquatic plants and uses freshwater as well as brackish environments.

4. Dugong (Dugong dugon)

The dugong is the only living member of the family Dugongidae. It inhabits tropical and subtropical coastal waters across the Indo-Pacific region. Unlike manatees, dugongs depend heavily on seagrass meadows. Their downward-facing snouts and forked tails make them particularly distinctive.

Extinct sirenians

Several extinct lineages provide important evidence of sirenian evolution.

• Prorastomus: An early Eocene sirenian that retained several features associated with land-dwelling mammals.
• Pezosiren: A four-limbed early sirenian that combined terrestrial and aquatic adaptations.
• Protosiren: An extinct genus that represents a more aquatic stage in early sirenian evolution.
• Hydrodamalis gigas: The Steller's sea cow, a giant relative of the dugong that once inhabited the North Pacific.

Georg Wilhelm Steller documented the Steller's sea cow during the eighteenth century. Unfortunately, intensive hunting for its meat, fat, and hide rapidly reduced its population. The species became extinct in 1768, only a few decades after its scientific discovery. These living and extinct species reveal the remarkable evolutionary diversity that once existed within Sirenia.

Habitats, Ecology, Conservation, and Ecological Importance

Sirenians inhabit a variety of warm aquatic environments. Their distribution depends on several factors, including water temperature, food availability, habitat structure, and access to suitable feeding and breeding areas.

Manatee habitats

Manatees occupy freshwater rivers, lakes, estuaries, lagoons, and coastal marine environments. West Indian manatees use both saltwater and freshwater habitats. Similarly, African manatees inhabit a mixture of coastal and inland waters. Amazonian manatees, however, live exclusively in freshwater systems and depend on the rivers and floodplains of the Amazon Basin.

Dugong habitats

Dugongs primarily inhabit marine environments. They prefer shallow coastal waters where seagrass meadows provide suitable feeding grounds. Consequently, their distribution closely follows healthy seagrass ecosystems, particularly across the Indo-Pacific region.

Ecological importance

Sirenians influence aquatic environments through their feeding activities. By consuming aquatic vegetation, they help regulate plant growth and influence the structure of underwater habitats.

For example, dugongs create feeding trails in seagrass meadows as they remove vegetation from the seabed. This grazing activity can affect plant regeneration and nutrient cycling.

Manatees also influence freshwater and coastal vegetation communities through their feeding behavior. Furthermore, sirenians contribute to nutrient movement and aquatic food-web relationships. Their presence can also provide valuable information about the condition of some coastal and freshwater ecosystems.

Major conservation threats

Despite their ecological importance, sirenians face several serious threats.

1. Habitat loss and degradation

Coastal development, dredging, pollution, and damage to seagrass meadows reduce the availability of suitable feeding and resting areas. As a result, animals may struggle to find enough food or suitable places to raise their young.

2. Boat collisions

Fast-moving boats can strike manatees in shallow coastal waters and rivers. Such collisions may cause severe injuries or death. Therefore, boat-speed restrictions in important manatee habitats can help reduce this threat.

3. Fishing activities

Entanglement in fishing nets and other equipment can prevent sirenians from reaching the surface to breathe. Accidental capture therefore poses a serious risk to several populations.

4. Water pollution

Industrial waste, agricultural runoff, plastic debris, and other contaminants can damage aquatic habitats. These pollutants may also affect the health of sirenian populations and reduce food availability.

5. Climate and environmental change

Changes in water temperature, sea level, and coastal ecosystems can affect the distribution and quality of feeding habitats. In addition, extreme cold events can threaten manatees in regions where suitable warm-water refuges are limited.

6. Hunting and human disturbance

Although legal protection has reduced hunting in many areas, illegal killing and human disturbance continue to affect some populations.

Conservation efforts

Protecting sirenians requires maintaining healthy aquatic habitats and reducing human-related mortality.

Important conservation measures include:

• Establishing protected marine and freshwater areas.
• Preserving seagrass meadows and aquatic vegetation.
• Reducing boat speeds in important manatee habitats.
• Improving fishing practices to prevent accidental entanglement.
• Monitoring populations and rescuing injured animals.
• Reducing pollution and restoring degraded waterways.
• Supporting international cooperation and wildlife protection laws.

All living sirenian species face conservation concerns, but their population trends and threat levels vary by species and region. Consequently, conservation plans must consider local habitat conditions and population data rather than treating every sirenian population in the same way.

Protecting these mammals also helps preserve aquatic ecosystems on which many other species and human communities depend.

Conclusion

Sirenians represent a remarkable group of aquatic mammals that demonstrate how terrestrial ancestors can evolve into animals fully adapted to life in water. Their specialized flippers, reduced hind limbs, powerful tails, dense skeletons, and herbivorous feeding structures reflect millions of years of evolutionary change.

Their fossil record reveals the transition from four-limbed early forms to modern manatees and dugongs. Moreover, their evolutionary relationships with elephants and other Afrotherian mammals reveal important connections within placental mammal evolution.

Today, the four surviving species occupy important ecological roles in marine, coastal, and freshwater environments. Through their feeding activities, they influence aquatic vegetation and contribute to the functioning of these ecosystems.

However, habitat destruction, boat collisions, fishing activities, pollution, and other human pressures continue to threaten their survival. Therefore, protecting sirenians requires effective conservation measures and the preservation of healthy aquatic habitats.

By studying Sirenia, scientists gain a better understanding of mammalian evolution, aquatic adaptation, biodiversity, and the importance of conserving vulnerable marine and freshwater ecosystems.