This colorful animal bears the German name “Searache” because of its reptile-like shape and wing-like back appendages. In reality, it is a fish closely related to the seahorses.
Sea dragons (Phyllopetryx taeniolatus) occur in only one region worldwide: They live in the seaweed and seagrass meadows off the west and south coast of Australia. Their coloring and leaf-like appendages are a perfect camouflage in this environment for the shrimp and other small aquatic-eating sea dragons. The almost 50 centimeter long seahorse relatives let themselves drift in the water and thus approach their prey unobtrusively, then they suck in the shrimp in a flash with their tube-like elongated mouth.
In addition to their toothless, tubular mouth, the sea dragons also differ from “normal” fish in a few other features. They have lost the pelvic fins and tail fins typical of fish, as well as their scales, but they have a bony armor that envelops the whole body. The sea dragons, also known as small shredded fish, do not swim horizontally through the water, but glide slowly, almost vertically – like a horse – with their heads down through shallow coastal waters. With their curly tail they can – like monkeys – hold on to objects.
A team of researchers with the help of Axel Meyer from the University of Konstanz recently investigated the genetics behind these special adaptations of the sea dragons. Among other things, the scientists were able to determine that the rag-like attachments of the sea kites are due to converted fin rays. They owe their toothlessness to the loss of several genes, the several genes that contribute to the development of teeth in other fish and also in humans.
It is also typical of the seahorse family that the males carry the fertilized eggs. While seahorses have already developed a brood pouch for this purpose, the sea dragons, which are older in evolutionary history, still carry the sticky eggs visibly under their tails. Also interesting: The sex of the sea dragons is not determined by sex chromosomes as is the case with most mammals. Instead, a special hormone, the Mullerian hormone, determines whether a male or a female develops in them and in the seahorses.