- Being able to fly;
- Living in colonies with division of labour;
- Having long antennae that allow an animal to feel its way along in the dark;
- Different breeding strategies e.g. making nests, bearing live young; and
- Lack of planktonic larval phase which probably facilitates rapid speciation (i.e. local populations can be reproductively isolated.
So why aren’t insects dominant? The answer to that question would need a book but one chapter in the book would be the ability of animals to match their activity with the tides.
When I was young, I created a small mangrove swamp in a fish tank and kept fiddler crabs. Even though the fiddler crabs were separated from the sea, they still knew about the tides times and would make their little doors which they use to seal themselves in their burrows at high tide. In the wild it is easy to observe fiddler crabs closing their burrows before the advancing tide. Whether they just use their internal clock or whether they pick up environmental cues as well, I do not know but tides are complex so I suspect that the crabs use both. East coast Queensland has two high tides a day but the Gulf of Carpentaria has only one high tide a day. At the tip of Queensland, where the two seas meet it can be high tide in one and low tide in the other which results in the famous horizontal waterfall. Thursday Island which is three kilometres long can have high tide at one end and low tide at the other. It would interesting to see if fiddler crabs from one end of the island measure tides differently to those at the other
If fiddler crabs are masters of telling the tide, what do ants know? I found an ant trail of the mangrove swimming ant (Polyrhachis sokolova) and decided to watch how the ants reacted to the incoming tide. The trail was about 20 m long and ended at a tree on the seaward fringe.
|A mangrove swimming ant - Polyrhachis sokolova|
|Ant ascending tree at end of trail|
|Moment of truth - 1 second until the tide arrives - and still no reaction|
|Ant floating in a pool left by receding ripples|