Summer is here again and for most British animals the warm weather and abundance of food means that this is the best time to create a new life.
Large animals such as birds and mammals begin the process of reproduction during the winter, so that the babies are already growing. But many invertebrates (animals without backbones like insects and snails) are only just emerging from winter hibernation and the race is on to breed before the cold weather arrives again next winter.
It takes two to tango!
The Indian stick insect’s…eggs hatch without needing to be fertilised by a male, but all the offspring are identical to their mother and to each other. It is more usual to have a male and a female mate together before they can reproduce, but this makes life a bit more complicated! The first problem for small creatures in a big world is how to find each other. Then the pair must check that they are the right age, sex and species, or they will be wasting their time. The male may have to do some wooing to persuade the female he is the best choice to fertilise her eggs. For predatory animals, it is important that the male makes the right moves, or he might get eaten by his partner! These problems are solved by courtship. Invertebrates are born already knowing the correct courting behaviour, which can be long and complicated.
Sound of summer
Male dung flies lie in wait by fresh cow-pats where females lay their eggs. Other animals advertise their whereabouts by calling. Male crickets ‘sing’ loudly to attract a mate, by rubbing their wings together, and the chirruping noises are a familiar summer sound. The Chinese kept crickets in cages to hear the singing. Each species has a unique song, which only attracts animals of the same type…Mole crickets have specially designed burrows which amplify their churring sound. Females usually prefer the loudest males, as they are likely to be the biggest and strongest. Of course, there is the danger that another animal will hear the sound and come looking for a tasty meal, not a mate. Luckily, many of these invertebrates are also masters of disguise so are really hard to see.
You smell gorgeous!
Moths use scent to find each other in the dark. Their large antennae can detect irresistible chemical signals, called pheromones, over distances of a mile or more. Some male butterflies have scent scales on their wings which they shower over the female, to encourage her to mate.
Light of my life
Fireflies are beetles which use luminous patches on their body to find each other at night. Males fly around flashing the light at the tip of their abdomen. Each species has a specific pattern of flashes, like a Morse code. The wingless females reply from a branch. Some predatory glow-worms mimic female fireflies to lure the males and eat them. Sadly, fireflies also suffer from human disturbance. Nowadays street and car lamps cause light pollution through the night. This confuses and distracts the males, so sometimes they are not able to find females and fail to breed.
Variety is the spice of life
Two-spot ladybirds emerge from hibernation in May. Females are attracted by colour and pattern. Where the red ladybirds are more common, females prefer to choose black males to mate with, but in places where there are a lot of black types, the females prefer the red ones!
Choose your partner, do-si-do
A male scorpion does not get too close to his partner’s stinging tail. He holds the female’s pincers with his own and dances around with her, until he finds a good site to place a packet of sperm (a spermatophore). He drags the female over the spermatophore so that she picks it up by her genital opening. Once his mission is complete, the male runs away as quickly as possible.
Court or get caught
A male praying mantis has to be careful to avoid being eaten whilst mating. For the larger female, an extra meal is useful to nourish her eggs and give them a new start in life. The male usually approaches carefully from behind, then leaps onto her back, away from her forelegs. Fortunately, not many are ever eaten if they are careful.
The black widow spider gets her name because of the habit of eating the tiny males. But this is a very rare event which usually only happens to old or slow males. A male spider vibrates her web as he approaches so the female recognises him as a suitor, not as prey. If she has already mated, she may give signals to warn him she is not interested in his amorous advances. It would be best for the male if he understands that no definitely means No!
Adult male red-kneed spiders normally only have a year in which to mate before they die, so they try to find as many females as possible. The male taps his middle legs in a special rhythm on the ground when he gets near the female. When he gets really close he pushes her fangs away and uses his pedipalps (a pair of modified legs) to place sperm into the female’s abdomen, before rushing away. Although he is at risk of being eaten, the female also has to be careful as the mating position makes her vulnerable to attack. The correct courting behaviour reassures her that she is not in danger.
Source: Bain, Sandi. “Young Lifewatch”. Lifewatch magazine. Zoological Society of London [http://www.weboflife.co.uk]. Summer 1996.
Posted @ the Morons-world Weblog!
