Advances in genetics in recent years has revealed that many apparently exclusive pairs in fact sometimes mate with individuals other than their partner, but social monogamy is widespread.

Although little is known about mating systems in sharks and other cartilaginous fishes, there is evidence that some species such as tiger sharks (Galeocerdo cuvier) could be genetically monogamous.

Dwindling natural habitats are causing a significant decline in certain seahorse species. To bolster populations, researchers in Australia are building seahorse hotels and leaving the lights on.

BREEDING: Dwarf seahorses form monogamous pair bonds that are reinforced each morning ... relying on their camouflage to allow them to sit and wait to ambush creatures like fish fry, small crustaceans ...