Cyamidae – Whale lice

Might sound creepy at first, but these tiny crustaceans are actually fascinating creatures with a unique lifestyle that sets them apart in the animal world. Despite their name, whale lice aren’t lice at all—they’re amphipods, which are small, shrimp-like animals. What makes Cyamidae special is their exclusive relationship with marine mammals, particularly whales. These little hitchhikers live on the skin, scars, and folds of whales, feeding on dead skin, algae, and other debris. While that might sound parasitic, their presence is more like a clingy roommate than a harmful invader. Unlike most amphipods that swim freely or scavenge on the ocean floor, Cyamidae have evolved to live permanently attached to a moving home—an ocean giant.

Different species of whale lice prefer different kinds of whales. For example, gray whales have their own distinct species of whale lice, while right whales host different ones. Some whale lice are so host-specific that scientists can use them to track whale populations, migration patterns, and even family lineages. They cling to whales using strong, claw-like legs, which help them hold on even as their host swims at high speeds or dives deep into the ocean. Unlike many sea creatures that drift through the water, whale lice are entirely dependent on their host for life, spending their whole existence on the whale’s body.

Cyamidae also have a few surprising traits that make them stand out from other crustaceans. For one, they don’t go through a swimming larval stage like many marine invertebrates do. Instead, the babies are born as tiny versions of the adults and crawl onto the whale’s skin right away. They’re often found in large clusters around wounds, blowholes, or barnacles, which provide shelter and food. Scientists believe that some species even prefer scar tissue, where skin flakes off more easily. This means that the lice populations can be higher in whales that have had past injuries or entanglements. It’s a little gross, but incredibly useful for researchers trying to learn more about the whale’s life history just by looking at its skin companions.