Just Dive

🐢 Green Turtle Facts
Scientific name: Chelonia mydas
Name: Despite their name, green turtles aren't green on the outside. The name comes from the greenish colour of their body fat, caused largely by their diet.
Size: Adults commonly reach around 1–1.2 m in shell length and can weigh 100–150 kg, although some individuals get considerably larger.
Diet: Young green turtles are more omnivorous, but adults are primarily herbivores, feeding mainly on seagrass and algae.
Important ecosystem role: By grazing on seagrass, they help keep seagrass beds healthy and productive.
Long-distance travellers: Green turtles can migrate hundreds or even thousands of kilometres between feeding areas and nesting beaches.
Navigation: They have an impressive ability to navigate across the ocean and are believed to use the Earth's magnetic field as one of their navigation tools.
Breathing: They breathe air and can stay underwater for a long time when resting, but during active feeding or swimming they need to surface more frequently.
They don't have gills: Like all sea turtles, they must come to the surface to breathe.
Age: They can potentially live for many decades, but determining the exact age of an individual turtle is difficult.
Nesting: Females return to beaches to lay eggs, often returning to the same general region where they originally hatched.
Temperature determines s*x: The temperature of the nest during incubation influences whether hatchlings develop as male or female. Warmer nests produce more females; cooler nests produce more males.
Powerful swimmers: Their large front flippers provide most of the propulsion, while the rear flippers help with steering.
They can sleep underwater: Green turtles can rest underwater, often tucked beneath reef structures or other sheltered areas.
Shell: Their shell provides protection but is not an external skeleton—the ribs and vertebrae are incorporated into the shell structure.
No teeth: Instead, they have a hard, serrated-looking beak that helps them bite and tear food.
🌊 A great Sipadan/Mabul fact
Green turtles are particularly famous around Sipadan, where divers can encounter large numbers of them. They are often seen resting on the re

Glossodoris acosti

Scientific name: Glossodoris acosti

Common group: Dorid nudibranch (a type of colourful sea slug).
Family: Chromodorididae.

Distribution: Found throughout the tropical Indo-Pacific, including Malaysia, Indonesia, the Philippines, and Papua New Guinea.

Habitat: Lives on coral reefs and reef slopes, usually between 5–30 metres depth.

Diet: Feeds almost exclusively on certain species of marine sponges, often storing the sponge's defensive chemicals for its own protection.

Defence: Its bright colours are a warning to predators that it is toxic or unpalatable—a strategy known as aposematic coloration.

Breathing: Like all nudibranchs, it breathes through a feathery gill plume located on the rear of its body.

Senses: The two horn-like structures on its head are called rhinophores, which detect chemicals in the water to help it find food and mates.

Reproduction: Every individual is a simultaneous hermaphrodite, possessing both male and female reproductive organs. After mating, each can lay a delicate spiral ribbon of eggs.
Size: Typically grows to around 3–6 cm, though some individuals may be slightly larger.

Glossodoris acosti is a favourite subject for underwater photographers thanks to its striking colours and intricate patterns, making it a rewarding macro find on reefs around Sipadan and Mabul.

Nudibranch

Baby frog fish

Steven Mc Arthur Photography

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Co's Chromodoris

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Hermit crab

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🐚 General Facts
Not true crabs: Despite their name, hermit crabs aren’t “true” crabs — they lack a hard carapace on their abdomen and must use shells for protection.
Shell borrowers: They don’t make their own shells; instead, they occupy empty snail shells (and sometimes bottle caps or other objects) for protection.
Soft abdomen: Their curved, soft abdomen fits snugly into the spiral of a shell, which helps anchor them securely inside.
🌊 Habitat & Species
Two main types: There are marine hermit crabs (live in the ocean) and land hermit crabs (live on land but must return to the sea to breed).
Worldwide distribution: Found in tropical and subtropical regions around the world.
Land hermits and water: Land hermit crabs breathe through modified gills and must stay moist to survive.
🍽️ Diet & Behavior
Omnivores: They eat algae, decaying wood, dead fish, fruit, and even small invertebrates.
Scavengers: They play an important ecological role in cleaning up dead matter and waste in their environment.
Shell fights: When two hermits want the same shell, they’ll often “wrestle” or tap each other to decide who gets it.
🦀 Social Life
Not solitary: Despite the name “hermit,” many species are social and live in large groups.
Shell exchange chains: Sometimes, a group of hermits will line up from smallest to largest and swap shells in a “housing chain.”
🌱 Life Cycle
Marine larvae: Eggs hatch into free-swimming larvae that drift in the ocean before settling down.
Growth: As they grow, they must find larger shells — a critical part of survival.
Molting: They shed their exoskeleton several times as they grow. During molting, they often bury themselves for protection.
💡 Fun Facts
Longevity: Some land hermit crabs can live over 30 years in the wild!

Whip coral shrimp

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General Facts
Scientific name: Commonly Dasycaris zanzibarica or Pontonides ankeri, depending on the exact species.
Common names: Whip coral shrimp, wire coral shrimp, or wire-coral partner shrimp.
Family: Palaemonidae (the same family as many cleaner and commensal shrimps).
Habitat: Found exclusively on whip corals (genus Cirrhipathes and similar black corals) in tropical Indo-Pacific waters.
🌏 Distribution
Widely distributed throughout the Indo-Pacific region, including the Red Sea, Indonesia, Malaysia, Philippines, Papua New Guinea, and Great Barrier Reef.
Commonly seen by divers at depths of 10–40 meters.
🪸 Habitat & Behavior
Always found living on a single whip coral, often perfectly matching its host’s color and texture.
They cling tightly using their specialized legs, moving along the coral like tiny acrobats.
Usually solitary or found in pairs (a male and female).
🎨 Appearance
Length: About 1.5–2.5 cm.
Body: Slender and elongated to match the coral’s thin shape.
Color: Perfectly camouflaged — can be brown, white, yellow, green, red, or transparent, depending on the coral color.
Often have tiny spines or bumps that mimic the coral’s polyps.
🍽️ Diet
Likely feeds on mucus and detritus from the coral or planktonic particles caught by the coral’s tentacles.
May also scavenge small organic matter drifting in the water.
❤️ Reproduction
Usually live as monogamous pairs, with males smaller than females.
Females carry eggs on their abdomen, which hatch into planktonic larvae before settling on a new coral host.
⚔️ Defense & Camouflage
Their camouflage is their main defense — it’s nearly impossible to spot them unless they move.
Some species even match the polyps’ spacing and texture so well that they look like part of the coral.
📸 Fun Fact for Divers
Excellent subject for macro photography, but very tricky to spot.
Best seen when the coral is silhouetted against open water.

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General Information
Common name: Soft Coral Crab
Scientific name: Hoplophrys oatesii
Family: Majidae (Spider crabs)
Habitat: Found in tropical Indo-Pacific waters — commonly around Indonesia, Malaysia, the Philippines, and Papua New Guinea.
Depth range: Usually between 3–25 meters (can go deeper).
🌿 Appearance & Camouflage
These crabs live exclusively on soft corals, such as Dendronephthya.
They are expert mimics, often matching the color and texture of the coral they live on — including pinks, reds, yellows, and whites.
Their bodies are covered in small tubercles or spines that resemble coral polyps.
Some individuals even attach bits of coral tissue or polyps to their shell to enhance camouflage.
🍽️ Diet
Soft coral crabs are omnivores, mainly feeding on:
Plankton
Mucus and detritus around their coral host
Occasionally coral polyps or organic particles trapped by the coral.
🏠 Behavior & Lifestyle
They are nocturnal — more active at night, hiding during the day among coral branches.
Usually found alone or in pairs (sometimes a mating pair will share one coral colony).
Their close relationship with soft corals provides both protection and food.
🐣 Reproduction
Females carry brightly colored eggs under their abdomen until they hatch.
Larvae are planktonic, drifting in open water before settling on a coral host and taking on its color pattern.
⚠️ Conservation
While not considered endangered, soft coral crabs are vulnerable to coral reef damage caused by:
Climate change (coral bleaching)
Pollution
Over-collection in the aquarium trade.
🧠 Fun Facts
They are tiny — usually around 1–2 cm in size, often overlooked by divers.
Their mimicry is so precise that even experienced underwater photographers can miss them unless they’re moving.
They’re sometimes called “Candy Crab” due to their bright, coral-like coloration.