A Valentines Day look at how romance is alive and well in the animal Kingdom.
Cephalopod Courtship and Amorous Arachnids
Not only is it fun to say, but cephalopod courtship is fascinating and bears similarities to the activities of amorous arachnids. Both normally employ modified appendages, we can even call them arms, to perform the act.
We romantic humans tend to think of ourselves, or our fellow vertebrates as being the complex ones with beautiful displays and behavioural nuances. But, the more I learn about invertebrates, the more I feel that we are late comers to a stage where it has all been done before.
Those Crazy Cephalopods
Male cephalopods: cuttlefish, squid, octopus and nautilus produce spermatophores; watertight packages of sperm. You could be forgiven for calling it a cephalopod’s… ‘pod’. With the exception of nautiluses, this group of molluscs reproduce once and then die! Valentine’s day for them, whatever time of the year it may fall, is an all-important event.
The male has to deliver the spermatophore to the female, like a Valentines day gift (although it would be considered very blunt if we did this) and she has to be willing to take it. To deliver, he has a specially modified arm or arms, known as a spadix in nautilus and as a hectocotylus in most other cephalopods.
Sometimes the female has to physically take the package. In others, like octopus, he slips it under her mantle like a romantic ribbon wrapped love-letter going into lady’s pocket in a period drama. In order to convince her to accept the package, he has to dance or perform in some way in order to convince her that he is a worthy and eligible bachelor.
Nautilus But Nice!
For nautiluses, courtship is a fairly simple wrestling match in which the male simply needs to be fast enough and strong enough to bring the female face to face with him. So he can extend his spadix and she can accept the package.
Nautiluses can carry on breeding for several years, their eyesight is comparatively poor and they are fairly slow swimmers. Squid, cuttlefish and octopus on the other hand, have highly evolved eyes, powerful brains and nervous systems we humans are only beginning to understand, and mind-blowing colour changing abilities. Imagine you could change from a bridal gown, to a tuxedo, to a red suit of armour and then a jester’s costume in a few seconds without the use of your arms and you are in the realms of the abilities of cephalopods. Colours and textures dance across their skins.
Squid are the least dramatic in terms of texture change but what they lack in dermal-diversity they make up for with speed and drama. They are the most pelagic of cephalopods, living out in the open ocean often in large shoals and travelling at high speed. In some species the breeding season is a one-night event – yep, Valentine’s night – and the only chance in their life to breed, followed by sudden death.
It’s a sort of festival sized Romeo and Juliet that ends with a field full of babies and no adults! They are like living torpedoes, supremely streamlined and their courtship, though often very complex and colourful, can be so fast that it can only really be seen by looking at film and photographs afterwards; similar to me opening my wallet. Many species not only use colour and elaborate poses and manoeuvres, but also light displays using bioluminescent organs; also like a festival. They also emit aphrodisiac chemicals.
Octopus are benthic; they live on the seabed and often have lairs that they live in. Males may seek out female lairs or meet by chance while out and about. His hectocotylus mentioned above is a modified third arm (usually on the right in most species) which has a grove running along it, which takes the spermatophores along its length to a spoon like tip, called the ligula.
He puts on a display for the female, which may involve colour and skin texture change and him showing off the size of his suckers. Once accepted he inserts his ligula under her mantle and into the oviduct. The ‘package’ then travels from his internal reproductive organs, along the grooved hectocotylus to the ligula and into her oviduct where she stores it for later use. “Thank you sir, you can be on your way now.” Imagine if we did this. I’m picturing it done flamenco style.
With pelagic argonauts, close relatives of octopuses, the male dies as his special arm breaks off and the dismembered arm crawls in by itself. That would be pretty disturbing performed flamenco style. She looks after the arm as a store to fertilise her eggs, a macabre memento from a chance meeting in the vast ocean.
Last but not least are the cuttlefishes. They live part pelagic part benthic lives between the realms of octopus and squid. They probably have the greatest colour and skin texture changing abilities of all. Like all cephalopods, courtship varies among species but in UK waters males sometimes aggregate in large numbers around suitable egg laying sites and wait for females to arrive.
The males fight vigorously over females but also perform deceitful displays, such as, adopting the colour of a passive pattern of a female on one side of his body to fool a male rival, whilst display amorous intentions on the other, to female while he glides between the couple. Males will also use jets of water from their funnel to flush sperm from other males out of the female’s oviduct. All’s fair in love, it’s war!
On to the Arachnids
Male spiders usually produce a special little mat of silk on which they secrete their sperm. You can joke about this amongst yourselves, but it is unique among arthropods and makes spiders special. He then sucks it up with the modified tip of his front appendages, which look like little legs or feelers and are called pedipalps.
It’s a bit like filling a water pistol that’s hidden in a boxing glove. Somehow, he then has to convince the usually much larger female to allow him to put his pedipalp into her equivalent opening called an epigynum, which is located beneath her body a good way beyond her venomous fangs from his perspective. Sometimes he takes her a gift to keep her busy. Sometimes he dances and releases dazzling perfumes.
He is, of course, fair game as a meal once he has done the deed and has to scarper quickly and deftly if he is to sire any more spiderlings. This usually means him almost moon walking out of her lair. Contrary to popular belief though, most males get away. Most male spiders are smaller than females. They moult fewer times and therefore mature younger; they’re toy-boys!
Mature males can usually be distinguished quite easily by the ‘boxing-gloves’ on the end of their pedipalps, charged up and ready for mating. In some of the smaller species, the males do what baby spiders (spiderlings) do. They exude a strand of silk which floats on the breeze, whilst still attached to their body. The silk lifts them like a paraglider or kite up into the air and if they are lucky (or sense the right pheromones) they’ll land within reach of their Valentine.
Inordinately fond of stars and beetles
In the world of beetle conservation where I have spent a good deal of my time there is a much used quote, perhaps overused. Where the great scientist, mathematician and “Science Populariser” of the early 20th century, J.B.S. (Jack) Haldane, explained that what he knew of ‘The Creator’ was that he (or she) was or is, inordinately fond of stars and beetles.
Jack, I should tell you, was an atheist and was inordinately fond of repeating his stars and beetles quip, and why not? He was an early-ish proponent of the Primordial Soup theory; recently at least. Aristotle was pretty sure that life could be self-generating and the primordial soup was simply the liquid that seemed best fitted to fill Charles Darwin’s warm little pond.
Funnily enough, Charles was an obsessive beetle enthusiast too. Our planet, and life big enough to see on our rock in space, is dominated (despite the size and richness of beetleless oceanic life) by beetles in terms of number of species and that is what Jack Haldane was referring to. Perhaps every rock in space capable of sustaining (or generating) life is crowded with beetles too? Every star we can see could hold 10 million beetle species in orbit and every galaxy many billions more. If a creator did put them here, she (or he) also seems to have been inordinately fond of romantic diversity too and that is a big part of what I love about beetles.
More Beetle Romance
Many, such as the tansy beetle, dock beetle and those lovely orange red ones we see on summer flower heads, the soldier beetles, hook up in a copulatory position for many hours or even days.
In our largest beetles, stag beetles, the males use their enlarged mandibles like deer-antlers to fight for the attention of the female who watches. Don’t tell me this is not a human trait too or that it does not add something to romance. In many rom-coms these days our subjects use wit or intelligence to overcome rivals but it is still combat.
Glow-worms are snail-eating beetles and a great reason to maintain thickets and hedgerows for snails and their predators. Like a lonely damsel locked in a tower, the flightless female lights a light for a love she knows is out there. The males can fly and scout the land, as nocturnal aviators looking for lights like war-time bomber pilots. When they find their damsel they drop from the air immediately above her.
Burying beetles, attracted by the unmistakable aroma, meet at the carcass of a cadaver on a blind date and form a bond. As spouses they defend the body (the larder for their future family) from rivals whilst digging it into the ground. They strip it of fur and cover it with soil. After this brief encounter, the female drives the male away, burrows down to the carcass and lays her eggs, remaining there to care for their children who grow up without even a photo or a name for their Dad.
Dung beetles often live like married couples, dor beetles or dumble dors tend to burrow under the dung and take portions of it away into chambers. My favourite dung beetle is the minotaur. The male has three horns, more like a triceratops than a bull. He goes out roaming collects rabbit, deer and sheep droppings, rolling them home to his wife, who spends most of her time excavating the catacombs of their underground home. They seem as happy as pigs…
The Scarlet Malachite Beetle
I just want to finish this love note with a beetle we work with. Scarlet malachite beetles, the length of a little finger nail, are very rare in the UK and we have spent the best part of the last decade (and more) studying them.
Courtship takes place in meadows where the beetles often gather together in one small corner. The females are hungry for pollen and take a position, facing downwards on the flowering heads of grasses. They use other flower too sometimes but, in our experience, favour grasses and meadow foxtail in particular. There is always one female per grass head, often munching pollen but sometimes just waiting. We tend to watch and count them through binoculars, as they move around to the other side of the grass head if we approach and will fly away if we get too close.
Squabbles break out over grass heads as new females arrive or if one grass head goes to seed and another comes into flower. Males come zooming in and land on the stem below the female. If two males arrive they fight and the loser flies away. The victor approaches the female and starts nodding his head and the female may nod in response. I was surveying in a red tee shirt once and a female did the nodding dance for me. I was flattered, she was disappointed when she realised my unsuitability. The male approaches her until they are face to face, nodding ever more vigorously and then… they kiss! At least, it looks like a kiss. In fact is is part kiss and part locking of ‘antlers’.
The male has a special modification on his antennae which with the right kind of nodding, close enough, he catches her antennae in his. This allows her to taste a secretion from a gland on his face and assess his suitability for mating and only then will she allow it to happen. On a tiny scale, it is like flamenco again.
Romance can be happily dull, it is the sharing of a mutually enjoyable environment that makes us inordinately fond of each other. Happy Valentines Day.