Specimen Showcase | Dolphins Wear Masks Too?!

Recently, we received the skull of a Common Bottlenose Dolphin (𝘛𝘶𝘳𝘴𝘪𝘰𝘱𝘴 𝘵𝘳𝘶𝘯𝘤𝘢𝘵𝘶𝘴) 🐬from Hong Kong Ocean Park, a species commonly seen in marine parks or aquariums, as they adapt well in captivity. Their apparent smile makes them the stars of parks around the world 😊. Their common name came from the short and thick snout that resembles a bottle 🍼. They are grey in colour and reach around 3m in length.

Skull of common bottlenose dophin

As you can see on the pictures, their heads present a bulb, called melon, in front of their ocular orbits, which is part of the main sensory system for dolphins . Sound waves are generated through the melon and travel into the water. When the sonic waves come across any objects, they will bounce off and travel back, letting dolphins visualize their surroundings, a phenomenon referred to as echolocation 🔊.

Using melon for echolocation

But some of their favourite food may be very challenging to detect while using echolocation. Indeed, some molluscs such as octopus and cuttlefish 🐙🦑are difficult to locate because they hide underneath the sand and lack of swim bladders which lowers the effectiveness of echolocation. If dolphins have to look for these kinds of prey, they may need to probe the sand. And that’s exactly what they do. However, digging and rubbing around rough surfaces bear the cost of injuries for their rostra (beak). Interestingly, a population in Shark Bay, Western Australia, developed a particular behaviour allowing them to protect themselves while foraging for prey. They carry a marine sponge (Porifera) as a protective mask while probing the benthic floor 😲. With the use of these tools, dolphins are able to explore new niches and add new items to their menu!

Sponge as mask

Sponge as mask

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