Velikonoce

Velikonoce

Kaleidoskop zajímavostí



Nautilus pompilus

Detail srdečního cévního systému 




Specifikem tohoto hada je jeho ocas. Když byl v 60. letech poprvé objeven v Iránu, vědci se domnívali, že by se mohlo jednat o nádor. Výzkumy však ukázaly, že tento "pavouk" na konci ocasu hada slouží jako lákadlo kořisti. Had má pak mnohem lehčí práci při samotném lákání kořisti. Vědci však stále spekulují, proč se pavouk u hada vyvinul, když ostatním druhům stačí jejich obvyklý tvar ocasu.


Fotka Fotka: the Firefly's. Lampyridae is a family of insects in the beetle order Coleoptera. They are winged beetles, and commonly called fireflies or lightning bugs for their conspicuous crepuscular use of bioluminescence to attract mates or prey. Fireflies produce a "cold light", with no infrared or ultraviolet frequencies. This chemically produced light from the lower abdomen may be yellow, green, or pale red, with wavelengths from 510 to 670 nanometers. About 2,000 species of firefly are found in temperate and tropical environments. Many are in marshes or in wet, wooded areas where their larvae have abundant sources of food. These larvae emit light and often are called "glowworms", in particular, in Eurasia. In the Americas, "glow worm" also refers to the related Phengodidae. In many species, both male and female fireflies have the ability to fly, but in some species, females are flightless. Fireflies tend to be brown and soft-bodied, often with the elytra (front wings) more leathery than in other beetles. Although the females of some species are similar in appearance to males, larviform females are found in many other firefly species. These females can often be distinguished from the larvae only because they have compound eyes. The most commonly known fireflies are nocturnal,although there are numerous species that are diurnal. Most diurnal species are nonluminescent; however, some species that remain in shadowy areas may produce light. A few days after mating, a female lays her fertilized eggs on or just below the surface of the ground. The eggs hatch three to four weeks later, and the larvae feed until the end of the summer. The larvae are commonly called glowworms, not to be confused with the distinct beetle family Phengodidae or fly genus Arachnocampa. Lampyrid larvae have simple eyes. The term glowworm is also used for both adults and larvae of species such as Lampyris noctiluca, the common European glowworm, in which only the nonflying adult females glow brightly and the flying males glow only weakly and intermittently. Fireflies hibernate over winter during the larval stage, some species for several years. Some do this by burrowing underground, while others find places on or under the bark of trees. They emerge in the spring. After several weeks of feeding, they pupate for 1.0 to 2.5 weeks and emerge as adults. The larvae of most species are specialized predators and feed on other larvae, terrestrial snails, and slugs. One such species is Alecton discoidalis, which is found in Cuba. Some are so specialized, they have grooved mandibles that deliver digestive fluids directly to their prey. Adult diet varies. Some are predatory, while others feed on plant pollen or nectar. Most fireflies are quite distasteful to and sometimes poisonous to vertebrate predators. This is due at least in part to a group of steroid pyrones known as lucibufagins (LBGs), which are similar to cardiotonic bufadienolides found in some poisonous toads.

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