biology zoology blog benno meyer rochow plant gravity

Grappling with Gravity

A problem for plants

There can be no doubt that seedlings know that their roots have to grow down and their stems upward. This awareness of gravity seems to be maintained even in older plants, for if a young tree was lying flat on the ground (perhaps as a result of a storm), but with its roots still anchored in the soil, its tip would slowly bend upward in the months to come. Animals possess gravity receptors, statocysts, ear-stones; if they lack them they use their eyes and perceive the light from above, but plants? Where are their gravity sensors and where are their “eyes”? —>—>

biology zoology blog benno meyer rochow claws

Locked in, Locked up, Locked on…

Something that’s difficult to open

You can lock arms with someone, you can lock on to something or be locked in or even be locked up or locked out. But this essay is about animals that possess locking mechanisms. In the tropical waters of Ascension Island in the South Atlantic Ocean, for example, I once caught a pair of matchbox-sized trigger fish and observed their behaviour in my aquarium on board of the research vessel “Walter Herwig”. These denizens of the tropical seas as well as their cousins, the file fishes, can wedge themselves into rock cracks and coral crevices in such a way that it is virtually impossible to dislodge them by pulling at their tails. —>—>