Take a couple of specific habits (suction feeding on micro-crustaceans, hiding in beds of seaweed) and somehow evolutionary pressure yields a spiny-yet-delicate, sylvan-looking horse with leaves sprouting out of its epidermis.
Bow before our equine uber-Mom- the weedy sea dragon.
But do these factors really explain how this splendid, otherworldly-and-yet-familiar shape emerged from the Darwinian scrum? It’s essentially a circular argument.
I used to think that male brooding in sea dragons and their relatives was a simple matter of tending the fledglings. Not so. Once a male has received the eggs from a female, he provides the blood supply, oxygen, and nutrients. There might as well be an umbilical cord. Other than a technicality about which gametes are traded, the male IS the mother in all ways that matter.
First- male pregnancy appears to have evolved in multiple evolutionary lineages- see this fascinating article from researchers at Texas A & M (and clear all the noise about Johnny Manziel out of your head while you’re at it).
Secondly- male pregnancy in some of these species scuttles all the conventional rules about sexual selection. Females compete for males, and develop all the secondary characteristics (bright ornamentation, elaborate fins, etc.). Seahorses are an exception… the puritans of the sea, draping themselves in buff coloration and strict monogamy.
However, this doesn’t touch on the question of ‘why’, and nothing I’ve read really does. Anyone have a mechanism in mind? I’d love to hear about it.
You can thump on this thing just fine, though- its sound it sharp and barking like an Indian Tabla.
I should try to throw a didgeridoo on the wheel (now there’s a challenge) and put a sea dragon on the flank. The geography would match then.