Strange Parents asks how we usually recognise animals as either male or female and how each sex normally plays a particular role in their own life cycle. However, both hyenas and seahorses completely break preconceived gender rules.
This female-dominance seems to be linked directly to the care for cubs.
Hyaenas need strong jaws to crack bones. The architecture of the skull and the powerful muscles needed take years to develop, leaving young hyaenas almost helpless when it comes to obtaining food. They must look to their mothers for sustenance and rely on their ability to dominate kill-sites.
With the head of a horse, eyes like a chameleon, the prehensile tail of a monkey, armour that can change colour and possibly most remarkable of all, a brood pouch in the males, seahorses are astonishing creatures.
The startling discovery of this pouch and that male seahorses have a very surprising role as a new-age father forms one of the most curious stories of all.
Male seahorses become "pregnant", harbouring the females eggs in their pouch, and then experience contractions as they give birth.