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There are
three main aspects of cockroach social life • Protection • Fighting •
Communication
These three social characteristics change
through life, as shown on the following diagram [figure 1].
The life line [Figure 2] shows you what stages there are.
Mother Cocky is protected by his mother as an egg, so we start before he is born – as an egg case extruded by his mother [photo 5]. She twists the ootheca round [photo 6] so that it lies along the abdomen instead of across it. The advantage is protecting the young for longer. She keeps it safe inside her until it is ready to hatch, with Cocky’s 30-60 brothers and sisters. Even if you boil the ootheca, the eggs will still hatch out and become perfectly normal cockroaches.
Small
roaches are sheltering under the adults, mainly directly under them [photo 7].
They use the spines on the adults’ legs to protect them, as well as the
adult’s hissing warning system. They shelter under any adult for protection.
Cocky can’t communicate through hissing yet: he’s not physically
ready: he is not strong enough to propel air through his spiracles fast enough
to make the hissing sound. Young
male Young cockroaches do not practice fighting, unlike most young animals. They are still protected rather than protecting.
Cocky’s
final moult [photo 8]. The exoskeleton is eaten for its important nutrients.
When Cocky had his final moult, he started to fight, and to hiss to attract a
mate.
Dominance Here is
Cocky, now an adult, fighting with Mr Madder, the dominant male of my colony
[photo 9]. Cocky is the small one on
the left. How they fight: • Push fight: photo 8 showed Cocky and Mr Madder push fighting. Cocky is too small to dominate, but he tried! • Attack antennae: they attack each others’ antennae to prevent mating: they cannot smell the females without antennae. Cocky has already lost half his left antenna. • Hissing attracts females: hissing is important as females don’t mate with silent males. We know this because an experiment was done where an entomologist bunged up the hissing spiracles with glue so that they couldn’t hiss and were forced to live outside the social group. •
Old
Age
So, you see, a cockroach isn’t all just icky. It’s a very social creature. It is so well adapted to life that it has not changed for 400 million years or more. The three
aspects which make them social have helped them adapt and survive. Protecting each other and using fighting and hissing to select the best mate has helped them become successful. Even though cockroaches have not needed to change physically, they have become widely diverse, to fill all of the little evolutionary places and all types of habitat you could possibly think of all round the world: and being social has helped them to do this. |