The Goby and the Shrimp: Underwater Naturalist Specialty

I learned a fun fact in preparation for my Underwater Naturalist specialty. Some species of gobies and shrimp share a symbiotic relationship as roommates. The shrimp does the heavy digging, building and maintaining a burrow in the sand, while the goby stands guard at the entrance. Because the shrimp has poor eyesight, it often stays in contact with the goby using its antennae. If danger lurks, the goby signals or darts back inside, and both animals retreat into the safety of the burrow. Some studies suggest that the shrimp may benefit from food traces or goby droppings inside the burrow. Here are a few more fun facts.

Groupers and Moray Eels on the Hunt

I’ve also witnessed this one before. Groupers have been observed recruiting moray eels to help them hunt. The grouper patrols the open water while the moray searches through cracks, crevices and hiding places that the grouper cannot enter. Together, they cover more hunting ground than either could alone. It is one of the reef’s best examples of cross-species cooperation.

Nudibranchs Steal Defences from their Prey

Certain species of nudibranch feed on stinging animals such as hydroids or anemones. Instead of being harmed by the stinging cells, they can store those cells in their own tissues and use them later for defence. Nudibranchs are part of the sea slug family, which are still surprising scientists. In 2024, researchers described a deep-sea bioluminescent nudibranch found in the “midnight zone” off the Pacific coast.

Pufferfish and Sandy Crop Circles

Marine researches once observed these perfectly symmetrical patterned circles on the bottom of the sandy ocean floor. They eventually discovered that these relatively large artworks were created by tiny male pufferfish in an attempt to attract a female swimming above. If the female approves of the elaborate circular design, she lays her eggs dead in the center.

The Powerful Punch of the Mantis Shrimp

I love watching Mantis Shrimp. Dare to keep one in an aquarium (which you shouldn’t) it will smash the glass with one solid punch. Mantis Shrimp stun their prey with an incredibly fast and powerful punch. This can create cavitation bubbles – tiny vapour bubbles that collapse with a burst of force and heat. This means the prey can be hit twice: once by the limb itself and again by the collapsing bubble.

Butterflyfish Mate for Life

I love telling people this before leading a dive. Butterflyfish mate for life. They are therefore often seen swimming about in pairs. They stay close to their life partner at all times. If you spot one all alone, then sadly tragedy has befallen it’s partner… The good news is that many butterflyfish have a dark stripe through the eye and a fake eyespot near the tail. This may make predators strike at the wrong end, giving the fish a better chance to escape in the correct direction.

Standing on Parrotfish Poop

Some might already know this, but that soft white sand that form some of the most beautiful beaches in the world, is largely comprised of Parrotfish excrement. Parrotfish eat algae off coral and rocks with their powerful beak-like mouth. In the process, they also bite off tiny bits of calcium carbonate. After digestion, they excrete that as fine white sand that eventually washes up on beaches. It’s all very romantic.

Clownfish and Sex Changes

I love how fearless Clownfish are. Get too close to their anemone and they will go straight for your face! Clownfish live in a strict social hierarchy. In a typical group, the largest individual is the female, the next largest is the breeding male, and the smaller fish remain non-breeding. If the female disappears, the breeding male can change sex and become the new female. One of the smaller males then swims up the social ladder.

These are all of course discoveries that have already been made, but the Underwater Naturalist specialty will allow for this type of guiding. I’m sure I will learn more once I begin the course!

Next: Self-Reliant SCUBA Diver Achievement Unlocked

Previously: Hauling Gas – Dive Instructor Training in Mauritius