Dugong: The Gentle Sea Cow of the Ocean

Discover the dugong—the aquatic cousins of elephants—crucial marine herbivores whose survival is under threat. This article examines their distinct physiology, their vital role in ocean health, and the important conservation challenges facing their future.

Key Takeaways

• Dugongs are large marine mammals closely related to elephants, primarily feeding on seagrass and are known for their gentle nature and distinctive social behaviors, including complex communication through sounds.

• They inhabit warm coastal waters in about 37 countries and are considered environmental indicators, with their presence signifying a healthy marine ecosystem. Key habitats include the Great Barrier Reef and Australian waters, where dugong populations play a crucial role in the health of seagrass meadows.

• Dugongs are listed as vulnerable due to threats such as habitat loss, bycatch, boat collisions, and noise pollution, and require protective measures like cleanup events, habitat preservation, and international conservation agreements to ensure their survival.

Dugong Overview

Dugongs, affectionately named after the Malay term for ‘Lady of the Sea,’ belong to the Sirenia species and share a closer relation to elephants than to other marine mammals like whales and dolphins. These large, grey-brown animals, including female dugongs and male dugongs, feature:

• a broad, flat muzzle with a mouth angled downwards, aiding them in their unique feeding habits along the seabed

• a streamlined body with a horizontal tail fluke for propulsion

• paddle-like flippers for steering and maneuvering in the water

Despite their hefty size, often weighing around 400 kilograms, the dugong’s brain is relatively small, weighing in at only about 300 grams.

Dugongs are not just physically fascinating; they also exhibit intriguing social behaviors. They communicate with each other using a range of sounds, including chirps, whistles, and barks. This auditory interaction underscores their social behavior within their natural habitat, showcasing their complex communities and rich social lives.

From the dugong’s physical attributes to their social behavior, it’s clear that these creatures are truly unique. Their existence adds a touch of magic to the ocean’s vast biodiversity, yet they remain a mystery to many. So, you might wonder about the interaction of these ‘Ladies of the Sea’ with their marine environment. We will delve into this subject next.

Physical Features

Dugongs possess a distinctive cylindrical body shape, complemented by fluke tails and paddle-like forelimbs known as flippers. These physical characteristics equip them to maneuver through the marine environment, despite their size. Indeed, adult dugongs can reach up to 3.5 meters in length and weigh as much as 900 kilograms.

Their head is notably shaped with small eyes and ears, which corresponds with their reduced dependency on vision and hearing in their daily activities. Their poor eyesight is offset by their other sensory adaptations, which help them navigate and forage in their aquatic home. These adaptations are closely related to their unique environment and lifestyle.

The unique behaviour of dugong calves adds a charming element to their physical attributes. Much like human infants sucking their thumbs, dugong calves nurse by sucking on their own flippers, hinting at their nurturing behaviour and the extended care they receive from their mothers.

Swimming Style

Observing a dugong swim is an experience like no other, akin to a ballet performance under the sea. As one of the fascinating aquatic mammals, they utilise their fluke tail in a whale-like manner as their primary means of propulsion through the water. Their front flippers work similarly to dolphins’ pectoral fins, aiding in steering and stabilisation while swimming.

Despite their hefty size, dugongs can swim at speeds of around 10 kilometres per hour, contributing to their elegant locomotion. They navigate the shallow waters with grace and agility, moving effortlessly through their seagrass-filled stage. Yet, the beauty of their swimming style masks the potential danger of accidental drownings, a threat they face due to their reliance on air for breathing.

Distribution and Habitat

Dugongs are widespread, inhabiting warm coastal waters in about 37 countries worldwide, mostly north and south of the equator. Australia holds a significant portion of the dugong population, with estimates suggesting that its waters could contain up to 80,000 dugongs, making it a critical habitat for these gentle sea creatures. It is in these regions that dugongs occur most frequently.

In Australia, dugongs can be found in a wide arc from the Queensland/New South Wales border across to Shark Bay in Western Australia, with some venturing as far as southern New South Wales and near Perth. Dugongs display a preference for shallow bays and areas protected by large inshore islands and are known to travel long distances along the Australian coast.

The connection between dugongs and their habitats is not just about survival but also about the vital role they play in the ecosystem. They are often considered as environmental indicators, with their presence signalling a healthy marine environment and their absence reflecting problems within the ecosystem.

But where in Australia can you best encounter these charismatic creatures? We will investigate more on this.

Great Barrier Reef and Northern Territory

The Great Barrier Reef, a world-renowned natural wonder, serves as a crucial feeding ground for dugongs. The Torres Strait region holds the most significant dugong habitat globally, with the largest seagrass meadow in Australia and a large central dugong population extending from Boigu Island to north of Badu and Moa Islands.

Limmen Marine Park stands out in the Northern Territory for its diverse marine life, including dugongs, which use the park as a rest area during breeding seasons. This region, along with the Great Barrier Reef, supports a significant portion of the dugong population in Australia, making it a hot-spot for dugong sightings.

The Great Barrier Reef and Northern Territory offer not only the spectacle of dugongs but also a lesson in the importance of preserving these habitats. The survival of dugongs is intertwined with the health of these regions, making their conservation vital for the future of these ‘Ladies of the Sea.’

Other Hotspots in Australia

Beyond the Great Barrier Reef and Northern Territory, other locations in Australia also support dugong populations. Some specific areas in Western Australia known to support dugong populations are:

• Shark Bay

• Ningaloo and Exmouth Gulf

• The Pilbara coast

• Eighty Mile Beach including Roebuck Bay

Shark Bay alone is home to 10% of the world’s dugong population, which can ideally be spotted between September and November.

Moreton Bay and Hervey Bay in Queensland are also known hot spots for encountering dugongs in Australia. These locations provide essential habitats for dugongs, showcasing the interconnectedness of dugongs and their environment and reaffirming the importance of protecting these areas.

Dugong Diet and Feeding Habits

A distinguishing trait of dugongs is their diet. They are strictly herbivorous marine mammals, feeding almost exclusively on seagrass. These ‘sea cows,’ including the now-extinct Steller’s sea cow, show a strong preference for seagrass meadows, which are essential to their diet. What’s fascinating is their ability to recall specific feeding grounds within these meadows and return to them even after extended periods.

The health of seagrass meadows is critical to the diet of dugongs, with climate change posing a significant threat by affecting the availability and quality of their food. Hence, the conservation of these meadows is not just about preserving a landscape; it’s about ensuring the survival of species like dugongs that rely on them.

Seagrass Consumption

To support their large size, dugongs can consume up to 40 kilograms of seagrass in a single day. This immense daily consumption underlines the critical relationship between dugongs and their marine environment. The Great Barrier Reef plays a significant role in feeding these gentle giants, offering 14 species of seagrass that form part of their diet.

The dugong’s seagrass consumption has a profound impact on the marine ecosystem. Their grazing helps maintain the health of the seagrass beds, promoting a healthy ecosystem that benefits a wide array of marine species. However, their reliance on seagrass also makes them vulnerable to changes in their environment, particularly those caused by human activities.

Feeding Techniques

The feeding techniques of dugongs reveal their adaptability to the marine environment. Dugongs have coarse, sensitive bristles on their upper lip, which aid them in locating food. These sensitive bristles are utilised by dugongs to feel for seagrass when foraging on the sandy seafloor.

Their feeding technique leaves distinctive feeding trails on the seabed, making it possible for researchers to track dugong movements and feeding habits. This unique interaction with their environment underlines the intricate relationship between dugongs and their habitat, providing a glimpse into their daily lives beneath the waves.

Reproduction and Lifespan

Dugongs, like other marine mammals, have a unique reproduction process. Dugong females have a single calf every three to seven years. The calf stays with its mother for up to 18 months. This low rate of reproduction contributes to the vulnerability of the species, making their conservation even more crucial.

Dugong calves stay close to their mothers, drinking milk and following them for up to two years. This extended period of parental care is a testament to the nurturing nature of dugongs, further enriching their social behaviour.

In terms of longevity, dugongs take between 4 to 17 years to reach adult size. They are long-lived creatures, with some reaching the age of 70 years, adding another element to their fascinating life cycle.

Swimming and Diving with Dugongs

For those seeking a unique wildlife experience, swimming and diving with dugongs offer just that. These activities provide a rare opportunity to observe these gentle creatures in their natural habitats, interacting with their environment in a way that few other experiences can match.

However, it’s vital not to forget that these are wild animals in their home, and interactions should be respectful and cautious to protect their safety and wellbeing.

Best Destinations

If you’ve been inspired to swim or dive with dugongs, several destinations worldwide are renowned for these opportunities. Some of the best locations include:

• Marsa Alam in Egypt

• Coron in the Philippines

• Australia

• Bahrain

• Andaman Islands in India

• North Sulawesi in Indonesia

• Efate in Vanuatu

• Palau in Micronesia

• Raja Ampat in Indonesia

• Timor-Leste

• Kalpitiya in Sri Lanka

These locations offer exceptional dugong encounters.

In Australia, Ningaloo Reef in Western Australia stands out. This area offers tours that not only provide the chance to swim with:

• dugongs

• dolphins

• humpback whales

• whale sharks

These destinations offer a once-in-a-lifetime opportunity to swim alongside these tranquil sea creatures, fostering a deeper understanding and appreciation for them.

Responsible Interaction

Interacting with dugongs in the wild is a privilege that comes with responsibility. Best practices include:

• Keeping a safe distance

• Staying quiet

• Moving slowly

• Practice passive interaction

Being mindful of fin kicks and considering taking an eco-dugong tour can help ensure that your encounter is both rewarding and respectful.

When snorkelling or diving near dugongs, you should:

• Maintain a distance of at least 50 meters.

• Move slowly to avoid disturbing them.

• Allow for passive interactions where the dugongs control their level of engagement

Touching dugongs or any marine life, including migratory species, during water sport excursions is not recommended and is protected by law in most countries, emphasising their status as legally protected marine and migratory species.

The Vanuatu Environmental Science Society offers guidelines and a code of conduct in multiple languages, designed to foster positive and legally compliant interactions between people and dugongs. These guidelines serve as a reminder that our fascination with these creatures should always be balanced with respect and consideration for their wellbeing.

Conservation Efforts and Threats

Dugongs face significant threats that put their survival at risk. These include:

• Habitat loss due to activities like coastal settlement, shipping, trawling, and natural disasters

• Being inadvertently caught as bycatch in fishing operations

• Suffering collisions with boats and watercraft

• Noise pollution which interferes with their communication

These threats need to be addressed in order to protect the endangered species, particularly the dugong population.

The slow population growth and recovery from decline, compounded by their dependence on seagrass, puts dugongs at a high risk when facing threats, particularly as they experience low breeding rates, require long-term care of their calves, and have long intervals between births. The plight of dugongs underscores the need for urgent conservation efforts.

Vulnerable Status

Dugongs are listed as vulnerable species on the IUCN Red List, with an overall population trend that is decreasing. The vulnerability of dugongs is exacerbated by human-induced factors such as habitat destruction, being inadvertently caught in fishing nets, and illegal hunting. Their classification as vulnerable is further compounded by the dugongs’ low reproduction rates and the necessity for a long period of care for their offspring.

This vulnerable status serves as an alert for everyone. It highlights the pressing need for dugong conservation, as well as the protection of these gentle sea creatures and the habitats they inhabit. Protecting dugongs involves not just direct actions but also addressing larger environmental issues, such as climate change and habitat degradation.

Protecting Dugongs

Efforts to protect dugongs come in various forms, including:

• Participating in trash cleanup events to help protect dugongs and their habitats

• Avoiding movement through shallow seagrass areas to prevent damage to their essential habitats

• Supporting conservation organisations dedicated to safeguarding marine life, which contributes to the protection of dugongs.

Conservation efforts also include protected status under various acts and conventions, such as the EPBC Act in Australia and listings on CITES Appendix I and CMS Appendix II. Guidelines and memorandums from organisations like the Great Barrier Reef Marine Park Authority and the Memorandum of Understanding on the Conservation and Management of Dugongs provide a framework for concerted efforts to protect dugongs.

Summary

In exploring the world of dugongs, we’ve journeyed through the waters of their habitats, delved into their unique traits and behaviours, and uncovered the threats they face. We’ve also seen the efforts taken to protect these ‘Ladies of the Sea’ and the actions we can take to contribute to their conservation. Dugongs, with their serene demeanour and fascinating characteristics, remind us of the wonders of marine life and the importance of preserving it. Let their story inspire us to dive deeper into understanding and protecting our oceans, the home of these gentle sea cows.

Frequently Asked Questions

What are dugongs?

Dugongs are marine animals closely related to manatees, resembling them and are part of the Sirenia species. They share a closer relation to elephants than other marine mammals and are often referred to as the 'Lady of the Sea.'

Where can dugongs be found?

Dugongs can be found in about 37 countries worldwide, with the largest population found in Australia, particularly in areas like Shark Bay in Western Australia and near the Queensland/New South Wales border.

What do dugongs eat?

Dugongs are herbivorous marine mammals that mainly feed on seagrass, consuming up to 40 kilograms in a day.

How can we interact responsibly with dugongs?

To interact responsibly with dugongs, it is best to keep a safe distance, move slowly, and practice passive interaction. Avoid touching dugongs or any marine life during water sport excursions, as this is protected by law in most countries.

How can we help protect dugongs?

You can help protect dugongs by participating in trash cleanup events, avoiding moving through shallow seagrass areas, and supporting conservation organisations. These actions can contribute to the conservation of dugong populations.