Coral Predators

Coral Predators

by Fahmi, AMD-B’s 2024 Divemaster Intern

Coral reefs are vibrant ecosystems, and like any environment, they have species that interact in different ways. Some creatures feed on corals as part of the natural balance of life on the reef. While it might seem concerning at first, this predation is usually just a part of maintaining a healthy ecosystem.

Coral-Predators-Crown-of-Thorns-Starfish

Key Coral Predators

Crown-of-Thorns Starfish (COTS):
The Crown-of-Thorns Starfish is one of the most well-known coral predators. These spiny creatures feed on coral polyps, digesting the living tissue and leaving behind the skeleton. While they’re a natural part of the ecosystem, outbreaks can lead to significant damage to coral reefs.

Parrotfish:
Parrotfish are famous for grazing on coral. Their strong, beak-like teeth allow them to scrape away pieces of coral, which they digest and later excrete as sand. While this sounds harmful, they also help control algae, preventing it from overtaking the reef. In moderation, their coral consumption is part of the reef’s healthy balance.

Drupella Snails:
These small snails feed on coral polyps and can leave marks on the coral. They usually don’t cause widespread damage but can be a part of the natural predation cycle on reefs.

Butterflyfish:
These colorful fish feed on soft corals and polyps. Their impact is relatively minor, and they’re another example of how coral predation is part of the reef’s life cycle.

Coral-Predators-Butterflyfish-Racoon

When Populations Get Out of Control

In most cases, coral predators are just a part of reef life. However, when their populations grow too large, they can cause significant harm. One example is the Crown-of-Thorns Starfish outbreaks. These outbreaks occur when the starfish population spikes, often due to factors like pollution or overfishing of their natural predators. During an outbreak, the starfish can consume large areas of coral, leaving behind dead coral skeletons.

Such outbreaks can severely weaken coral reefs, making them more vulnerable to other threats like climate change, ocean acidification, and storms. When the balance shifts too far, the reef can struggle to recover.

Manta Rays

Manta Rays: Their Life Cycle and Why They are Vulnerable

by Fahmi, AMD-B’s 2024 Divemaster Intern

Manta rays have a unique but slow reproductive process. Female manta rays give birth to live pups after a pregnancy lasting about a year. What makes them vulnerable is that they typically produce only one pup at a time and may take two to five years before reproducing again. Once born, the pup is left to survive on its own and spends nearly a decade growing and maturing. This slow reproduction rate means manta populations struggle to recover when their numbers are reduced.

Manta rays are highly migratory creatures, travelling vast distances in search of food and suitable habitats. While this behaviour is essential for their survival, it increases their exposure to various threats. Overfishing, entanglement in fishing gear, and habitat destruction—such as the loss of coral reefs that serve as feeding or cleaning stations—pose significant risks. Climate change and pollution also impact the plankton populations that mantas depend on for food, making their survival even more challenging.

Manta-Rays-Life

Why Manta Rays Matter

Although manta rays do not have a massive ecological role compared to species like sharks or corals, they contribute to marine tourism in a significant way. Destinations like Nusa Penida and Raja Ampat attract divers and snorkellers eager to witness these majestic animals. The revenue from manta ray tourism supports local economies and often funds conservation projects, creating a positive cycle of benefits for both humans and the environment.

Manta-Rays-Matter

The Importance of Protecting Manta Rays

Manta rays are not just symbols of marine biodiversity; they are also indicators of ocean health. Their vulnerability reminds us of the delicate balance in marine ecosystems. Protecting manta rays is not only about saving a species—it’s about safeguarding the health of our oceans, promoting sustainable tourism, and respecting the interconnectedness of life underwater.

Protecting-Manta-Rays

Nudibranchs

Nudibranch

When it comes to shapes and colours, the variations found in nudibranchs never ceases to impress underwater photographers – and the rest of us!

There are over 3,000 species of nudibranchs worldwide, with new ones being identified regularly. These fascinating creatures are hermaphrodites, meaning they can mate with any individual of their species. Another intriguing fact is that nudibranchs are carnivorous, with diets that go beyond corals, algae, anemones, and sponges—they may even consume other nudibranchs.

Nudibranchs in Indonesia

To help you get started, here are five fantastic nudibranchs to look out for in Indonesia:

Nudi-Hypselodoris-Bullocki

Hypselodoris bullocki – This species, found in Bali, Lembeh, Triton Bay, Wakatobi, and Ambon, is famous for its lavender hue and dark spots. It’s a beautiful find for those who appreciate subtle but striking patterns.

Nudi-Chromodoris-Magnifica

Chromodoris magnifica – As its name suggests, Chromodoris magnifica truly stands out. You can find this bold nudibranch in places like Raja Ampat, Ambon, Halmahera, Lembeh, and Bali. Its eye-catching combination of orange, white, and black makes it a favorite for underwater photographers.

Nudi-Nembrotha-Kubaryana

Nembrotha kubaryana – Known for its dramatic blend of black, green, and orange, Nembrotha kubaryana is another species divers love to spot in Wakatobi, Bali, Lembeh, Raja Ampat, and Alor.

Nudibranch-Doto-Greenamyori

Doto greenamyori – This unique species has earned the nickname “Doughnut Doto” because of its shape. Doto greenamyori can be found in Tulamben, Wakatobi, and Misool, often hiding among hydroids and other small organisms.

Nudi-Thecacera-Pacifica

Thecacera pacifica – With its bright yellow color and black markings, this nudibranch resembles the famous character Pikachu! You can find it in Bali, Triton Bay, and Alor.

Please note: The above are the areas which offer a high chance of seeing these particular nudis. This being Indonesia, you can find the most unexpected species far outside their known range, for example:
– While diving with AMD-B, Dr Richard Smith (Ocean Realm Images) found displaying male McCosker’s flasher wrasses 2,500km east of their previously recorded range
– Okenia liklik nudis in Tulamben Bay, Bali (previously only recorded in Papua New Guinea and Luzon).

There are many other super-rare nudis that are scattered throughout the ocean so, who knows, maybe YOU will be lucky enough to find a new species and contribute to naming it 🙂