The Daily Omnivore

A Brocken specter is the apparently enormous and magnified shadow of an observer, cast upon the upper surfaces of clouds opposite the sun. The phenomenon can appear on any misty mountainside or cloud bank, or even from an airplane, but the frequent fogs and low-altitude accessibility of the Brocken, a peak in the Harz Mountains in Germany, have created a local legend from which the phenomenon draws its name. The Brocken specter was observed and described by Johann Silberschlag in 1780, and has since been recorded often in literature about the region. The ‘specter’ appears when the sun shines from behind a climber who is looking down from a ridge or peak into mist or fog. The light projects the climber’s shadow forward through the mist, often in an odd triangular shape due to perspective.

The apparent magnification of size of the shadow is an optical illusion that occurs when the observer judges his shadow on relatively nearby clouds to be at the same distance as faraway land objects seen through gaps in the clouds, or when there are no reference points at all by which to judge its size. The shadow also falls on water droplets of varying distances from the eye, confusing depth perception. The ghost can appear to move (sometimes quite suddenly) because of the movement of the cloud layer and variations in density within the cloud. The head of the figure is often surrounded by the glowing halo-like rings of a glory, rings of coloured light that appear directly opposite the sun when sunlight is reflected by a cloud of uniformly-sized water droplets. The effect is caused by the diffraction of visible light.

Island gigantism is a biological phenomenon in which the size of animals isolated on an island increases dramatically in comparison to their mainland relatives. Large mammalian carnivores are often absent on islands, due to their large range requirements and/or difficulties in over-water dispersal.

In their absence, the ecological niches for large predators may be occupied by birds or reptiles, which can then grow to larger-than-normal size. Since small size usually makes it easier for herbivores to escape or hide from predators, the decreased predation pressure on islands can allow them to grow larger.

In zoology, deep-sea gigantism, also known as abyssal gigantism, is the tendency for species of crustaceans, invertebrates and other deep-sea-dwelling animals to display a larger size than their shallow-water counterparts. Examples of this phenomenon include the giant isopod, the Japanese spider crab, the king of herrings (an oarfish of up to 12 m), the Seven-arm Octopus, and a number of squid species, including the Colossal Squid (up to 14 m in length).

It is not known whether this effect comes about as a result of adaptation for scarcer food resources (therefore delaying sexual maturity and resulting in greater size), greater pressure, or for other reasons. The Blue Planet series posited that larger specimens do well in the abyssal environment due to the advantages in body temperature regulation and a diminished need for constant activity, both inherent in organisms with a lower surface area to mass ratio.