( Huenia heraldica )
Every kid’s told to ‘eat your greens’. The Halimeda crab does one better… it wears them!
The Halimeda Crab – or Arrowhead Algal Crab has evolved to mimic the Halimeda Algae, which is common in tropical reef environments. The algae grows into thick meadows interconnected by fine threads under the substrate, and contains calcium carbonate which makes it a delicacy for many reef herbivores. The tiny crab is also a favoured snack for many predators, so in many ways it’s strange it chooses a sought after meal as camouflage. The crab’s bright green colour matches the algae perfectly, and it possesses flaps on its legs and body that match the algae’s leaves. Its finishing touch is attaching an actual piece of algae to its head. The net result is a tasty crab served with an equally tasty side-salad; attractive to almost every reef creature!