Camouflage

Yesterday`s blog on Batesian mimicry got me started thinking (thus the big tank of air, brain activity requires oxygen!).  Batesian mimicry was about “parasitizing” on the true signal of something sending out an honest warning. This is a very special type of mimicry. Camouflage, where animals try to look like Read more…

Fluorescence and bioluminescence

When I arrived in Lembeh this time it was just after Christmas. However, I was up for another Christmas treat. Simon here from NAD had ordered a bunch of cool stuff from Nightsea, strobe filters, filters for the lens and a cool pair of yellow spectacles, which waited for me here.  I have now tried this system during my stay and will in this blog give a short overview over what I learned from shooting it. But first of all I want to give a brief explanation over what fluorescence is, and why we can find it in nature. BTW, the complete system is available for rent here in NAD if you wish to try it out.

Fluorescent hard coral

Fluorescent hard coral


First of all, fluorescence is often confused with bio-luminescence. Bio-luminescence is found in more and more animals, and in a number of mushrooms as well. Well-known examples are those of plankton giving of light when disturbed, deep-water organisms with light organs, mushrooms glowing in the forests, fire flies and for northern areas glowworms. Bio-luminescence is the emitting of light involving a chemical reaction. Very generally, the light emitting substance is a protein called luciferin, which emits light through a chemical reaction catalyzed and oxidized by an enzyme, called luciferase. Thus, a chemical provides the energy fueling bio-luminescence, using oxygen in the process.
Bioluminescing mushrooms

Bio-luminescing mushrooms


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Sexual selection – a driving force in marine systems?

Prey are well adapted to evade predators, and predators are correspondingly well adapted to catch prey. For most of us it is pretty reasonable to accept that such adaptation happens by natural selection, leading to long-term evolution of animals, making them better to either catch prey or evade predators, whatever end of the food chain you happen to be on. Thus natural selection affects traits such as foraging efficiency or anti-predator behaviours that lead to longer lives, quicker growth rates and, both directly and indirectly, higher reproduction rates. Most of my earlier blogs have more or less built on the assumption of natural selection affecting adaptations of animals.

Bright warning colour on nudibranch. Probably a result of natural selection favouring nudis clearly advertising their poisonous properties.

Bright warning colours on nudibranch. Probably a result of natural selection favouring nudis clearly advertising their poisonous properties.


There is  another kind of selection, sexual selection, that is a little bit harder to understand. Sexual selection is the process where traits that directly affect the likelihood of securing a mate is changed over time, leading to the evolution of traits that sometimes seem to act contrary to natural selection in that sexually selected traits rather decrease life expectancy and growth rates. There are many examples of traits governed by sexual selection on land. Bird song, brightly colored males in many birds and lizards, antlers on deer and males adapted for fighting other males for access to females are examples that we all can relate to. It is thought that sexual selection in terrestrial systems are well as important as natural selection in shaping many aspects of populations and also a major force in driving speciation. (more…)

TK delivers!

Whenever you visit the same dive area several times, some dive sites seem to consistently deliver more than others, and, correspondingly, some less than you would wish. Here in Lembeh my favorites are the Aer Bajo sites and Hairball, where many uneventful starts of dives have been turned around to Read more…