Valentines Day under the sea

February is the time of year for romance.

Think chocolates, red roses, and a candlelit meal for two. Yes, Valentine’s day is upon us and with it the opportunity for love – or a least a card from your mum.

For avid anglers, it’s also perhaps the one day of the year when in the interests of marital harmony it might be best to leave your carp fishing tackle in the cupboard.

But while we’re in a romantic frame of mind, we thought we’d take a fish’s eye view of the mating game. Just how do fish do it?

Love nest

Cichlids sandcastle

Image source: Kocher Lab
The cichlid’s sandcastle pad

A cichlid’s sandcastle is his love nest. In the attempt to attract a mate these African lake dwelling fish build up a carefully designed pile of sand that they defend from other males. The sandcastle pad is both a place to mate and somewhere to look after the eggs until they hatch.

Scientists studying the fish discovered that if they modified the shape of the nest or ‘bower’, the male it belonged to had less fights with other fish and was more likely to attract a female. Cichlid ladies it seems, are most attracted to a man who’s not afraid to show a bit of individuality.

Clingy partner

Angler fish

Image source: Fishes of Australia
Mini male angler fish latch on to females

The ultimate clinger on, the male angler fish administers a love bite that lasts. Because of the difficulty in finding a mate in the deep dark abyss, some species of male angler fish have developed the ability to literally become one with their mate.

Males use well their highly sensitive sense of smell to locate a female and bite into her skin. His mouth produces enzymes that digest both their flesh. The two fish grow into each other, the male living off the blood supply of the female. As a survival strategy it’s spot on. Whenever the female feels like reproducing, she has a mate ready to fertilise her eggs.

Top lady

clown fish

Image source: Wikipedia
In clown fish land, ladies rule

In clown fish communities, who gets to mate is all based on pecking order. Top fish is a female – the biggest and bossiest of the group. She only mates with one male fish. All the others have to wait their turn. When the leading female dies or is taken out by a predator, the top male changes sex to become the matriarch, and all the male fish below move up one notch.

As to when clown fish mate – the female waits for the silvery light of the full moon before laying her eggs on flat surfaces amid the garden of anemones where she lives. Who said romance was dead?

Chain reaction

sea hare

Image source: Sea hares have both male and female organs
Hermaphrodites who like a lot of love

Sea hares are gastropods with a soft bodies and internal shells. They’re a sort of shell-less sea snail. They can grow quite large – up to 75cm long and 2 kg in weight – and their long protruding nostrils prompted the romans to name them after the land animal.

When it comes to reproduction, sea hares are interesting because they have male organs at one end, female at the other. And when they mate, several of the creatures often link together, sometimes forming a circle of love.

Painful love

nautilus

Image source: William Patterson University
The male’s reproductive tentacle is broken off

The argonaut or paper nautilus is an octopus that resides in tropical waters. The female grows up to 10cm in length but creates a delicate calcite shell up to 30cm in diameter. The shell doubles as both a home and a brood chamber for eggs.

Mating with one of the tiny 2cm males of the species is an interesting process in that the male’s reproductive tentacle is broken off and presented to the female in its live, wriggling state.

Cupid

Giant Squid

Image source: Funny Junk
Fear not, this one’s a hoax!

Not much is known about how giant squid reproduce. For a long time scientists interested in discovering the mechanics of the creature’s mating process were baffled as to how males delivered their sperm to females.

But then a female specimen was found in Tasmania which may hold the answer to the riddle. Scientists examining the creature found dart-like tendrils attached to each of her legs. It seems possible that males shoot ‘love darts’ at their mates, injecting sperm through the female’s skin.