Black Mamba Snake
1. The black mamba (Dendroaspis polylepis) is a venomous snake endemic to parts of sub-Saharan Africa. Skin colour varies from grey to dark brown. Juvenile black mambas tend to be lighter in color than adults and darken with age.
It is the longest species of venomous snake indigenous to the African continent; mature specimens generally exceed 2 meters (6.6 ft) and commonly attain 3 meters (9.8 ft). Specimens of 4.3 to 4.5 meters (14.1 to 14.8 ft) have been reported.
Although most mamba species are tree-dwelling snakes, the black mamba is not generally arboreal, preferring lairs in terrestrial habitats in a range of terrains. These include savannah, woodlands, rocky slopes and in some regions dense forest. It is diurnal and chiefly an ambush predator, known to prey on hyrax, bush babies and other small mammals as well as birds.
It is also a pursuit predator; in this it resembles some other long, speedy, highly-venomous species with well-developed vision. Over suitable surfaces it is possibly the speediest species of snake, capable of at least 11 km/h (6.8 mph) over short distances. Adult mambas have few natural predators.
In a threat display, the mamba usually opens its inky black mouth, spreads its narrow neck-flap and sometimes hisses. It is capable of striking at considerable range and occasionally may deliver a series of bites in rapid succession.
Its venom is primarily composed of potent neurotoxins that may cause fast onset of symptoms. Despite its reputation for being formidable and highly aggressive, like most snakes, it usually attempts to flee from humans unless threatened or cornered. Not being proximal to humans, bites from the black mamba are not frequent.
The black mamba, Dendroaspis polylepis, is an elapid within the genus Dendroaspis. Although it had been known to missionaries and residents, prior to 1860, by the name “mamba”, which was already established in the vernacular and taken from the Zulu word “imamba“.
The first formal description was made by Albert Günther in 1864. In 1873, Wilhelm Peters described two subspecies: the nominotypical D.polylepis polylepis and also D.polylepis antinorii. However, these are no longer held to be distinct.
In 1896, Boulenger combined the species (Dendroaspis polylepis) as a whole with the eastern green mamba (Dendroaspis angusticeps), a lumping diagnosis that remained in force until 1946, when FitzSimons split them again into separate species.
The generic name, Dendroaspis, derives from Ancient Greek dendro (δένδρο), meaning “tree”, and aspis (ασπίς), which is understood to mean “shield”, but also denotes “cobra” or simply “snake”, in particular “snake with hood (shield)”.
Via Latin aspis, it is the source of the English word “asp”. In ancient texts, aspis or asp often referred to the Egyptian cobra (Naja haje), in reference to its shield-like hood.Thus, “Dendroaspis” literally means tree asp, reflecting the arboreal nature of most of the species within the genus. The genus was first described by the German ornithologist and herpetologist Hermann Schlegel in 1848.
Slowinski et al. (1997) pointed out that the relationships of the African genus Dendroaspis are problematical. However, evidence suggests that Dendroaspis, Ophiophagus, Bungarus, and Hemibungarus form a solid non-coral snake Afro-Asiatic clade.
Dendroaspis polylepis is a large, round-bodied, slender, but powerful snake. It tapers smoothly towards the tail, and is of markedly more robust build than its distinctly gracile congeners Dendroaspis angusticeps and Dendroaspis viridis.
The head is often said to be “coffin-shaped” with a somewhat pronounced brow ridge and a medium-sized eye. It is a highly proteroglyphous snake, with fangs up to 6.5 millimeters (0.26 in) in length located at the front of the maxilla.
The adult snake’s length ranges from 2 meters (6.6 ft) to 3 meters (9.8 ft) routinely but, according to some sources, specimens have grown to lengths of 4.3 to 4.5 meters (14.1 to 14.8 ft).Black mambas weigh about 1.6 kilograms (3.5 lb)on average.
A specimen of 1.41 meters (4.6 ft) was found to have weighed 651.7 g (1.437 lb).Dendroaspis polylepis is the second longest venomous snake species, exceeded in length only by the king cobra.
Specimens vary considerably in color; some are olive-brown to khaki, many are grey, but none are black. Some individuals display dark mottling towards the posterior, which may appear in the form of oblique bars.
The underbody is often pale yellow or cream colored and the eyes are dark brown to black with a silver or pale yellow corona surrounding the pupil. Juvenile snakes are lighter in color than adults, typically grey or olive green in appearance, and they darken with age.
2. Scorpions are predatory arachnids of the order Scorpiones. They have eight legs and are easily recognized by the pair of grasping pedipalps and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger. Scorpions range in size from 9 mm / 0.3 in. (Typhlochactas mitchelli) to 23 cm / 9 in. (Heterometrus swammerdami).
The evolutionary history of scorpions goes back to the Silurian era 430 million years ago. They have adapted to a wide range of environmental conditions and can now be found on all continents except Antarctica.
Scorpions’ number about 1750 described species, with 13 extant families recognized to date. Only about 25 of these species are known to have venom capable of killing a human being.:The taxonomy has undergone changes and is likely to change further, as genetic studies are bringing forth new information.
Scorpion stings are painful but are usually harmless to humans. For stings from species found in North America, no treatment is normally needed for healthy adults, although medical care should be sought for children and for the elderly. More harmful stings from species found in South America, Africa, and western Asia may require medical attention.
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There are thirteen known families and about 1,750 described species and subspecies of scorpions. In addition, there are 111 described taxa of extinct scorpions.
This classification is based on that of Soleglad & Fet (2003), which replaced the older, unpublished classification of Stockwell. Additional taxonomic changes are from papers by Soleglad et al. (2005).
Scorpions are found on all major land masses except Antarctica. Scorpions did not occur naturally in Great Britain, Japan, South Korea, New Zealand and some of the islands in Oceania, but now have been accidentally introduced in some of these places by human trade and commerce.
The greatest diversity of scorpions in the Northern Hemisphere is to be found in regions between the latitudes 23° N and 38° N.
Above these latitudes, the diversity decreases, with the northernmost natural occurrence of scorpions being the northern scorpion Paruroctonus boreus at Medicine Hat, Alberta, Canada 50° N.
Today, scorpions are found in virtually every terrestrial habitat, including high-elevation mountains, caves and intertidal zones, with the exception of boreal ecosystems, such as the tundra, high-altitude taiga and the permanently snow-clad tops of some mountains.
As regards microhabitats, scorpions may be ground-dwelling, tree-living, lithophilic (rock-loving) or psammophilic (sand-loving); some species, such as Vaejovis janssi, are versatile and found in every type of habitat in Baja California, while others occupy specialized niches such as Euscorpius carpathicus, which occupies the littoral zone of the shore.
Scorpions prefer areas where the temperatures range from 20 to 37 °C (68 to 99 °F), but may survive temperatures ranging from well below freezing to desert heat.
Most scorpions reproduce sexually, and most species have male and female individuals.
3. Box jellyfish (class Cubozoa) are cnidarian invertebrates distinguished by their cube-shaped medusae. Some species of box jellyfish produce extremely potent venom: Chironex fleckeri, Carukia barnesi and Malo kingi.
Stings from these and a few other species in the class are extremely painful and can be fatal to humans. Box jellyfish” and “sea wasp” are common names for the highly venomous Chironex fleckeri.
However, these terms are ambiguous, as “sea wasp” and “marine stinger” are sometimes used to refer to other jellyfish.
The medusa form of a box jellyfish has a squarish, box-like bell. From each of the four lower corners of this hangs a short pedalium or stalk which bears one or more long, slender, hollow tentacles.
The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell’s aperture and creates a powerful jet when the bell pulsates.
As a result, box jellyfish can move more rapidly than other jellyfish; speeds of up to six meters per minute have been recorded. In the center of the underside of the bell is a mobile appendage called the manubrium which somewhat resembles an elephant’s trunk. At its tip is the mouth.
The interior of the bell is known as the gastrovascular cavity. It is divided by four equidistant septa into a central stomach and four gastric pockets. The eight gonads are located in pairs on either side of the four septa.
The margins of the septa bear bundles of small gastric filaments which house nematocysts and digestive glands and help to subdue prey. Each septum is extended into a septal funnel that opens onto the oral surface and facilitates the flow of fluid into and out of the animal.
The box jellyfish’s nervous system is more developed than that of many other jellyfish. They possess a nerve ring around the base of the bell that coordinates their pulsing movements, a feature found elsewhere only in the crown jellyfish.
Although the notoriously dangerous species of box jellyfish are largely restricted to the tropical Indo-Pacific region, various species of box jellyfish can be found widely in tropical and subtropical oceans, including the Atlantic Ocean and the east Pacific Ocean, with species as far north as California, the Mediterranean Sea (for example, Carybdea marsupialis)and Japan (such as Chironex yamaguchii),and as far south as South Africa (for example, Carybdea branchi) and New Zealand (such as Copula sivickisi).
It has been found that the statoliths, which are composed of calcium sulfate hemihydrate, exhibit clear sequential incremental layers, thought to be laid down on a daily basis. This has enabled researchers to estimate growth rates, ages, and age to maturity.
Chironex fleckeri, for example, increases its inter-pedalia distance (IPD) by 3 mm (0.12 in) per day, reaching an IPD of 50 mm (2 in) when 45 to 50 days old.
The maximum age of any individual examined was 88 days by which time it had grown to an IPD of 155 mm (6 in). The box jellyfish actively hunts its prey (small fish), rather than drifting as do true jellyfish. They are capable of achieving speeds of up to 1.5 to 2 metres per second or about 4 knots (7.4 km/h; 4.6 mph).
A fully grown box jellyfish can measure up to 20 cm (7.9 in) along each box side (or 30 cm (12 in) in diameter), and the tentacles can grow up to 3 m (9.8 ft) in length. Its weight can reach 2 kg (4.4 lb).
There are about 15 tentacles on each corner. Each tentacle has about 500,000 cnidocytes, containing nematocysts, a harpoon-shaped microscopic mechanism that injects venom into the victim. Many different kinds of nematocysts are found in cubozoans.
Although the box jellyfish has been called “the world’s most venomous creature”only a few species in the class have been confirmed to be involved in human deaths and some species poses no serious threat at all.
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