Head is the term applied to the anterior part of the body of an animal when marked off by a difference in size, or by a constriction (neck). A gradual increase of complexity in the structure of the head is observable as we ascend from the lowest to the highest forms of life. In the Protozoa, Infusoria, and Coelenterates nothing that can be regarded as a head is found, and it is not until we ascend to the worms proper, the articulated animals (crustaceans, myriapods, spiders, and insects), the land and fresh-water gasteropods (snails and whelks), and the cuttle-fishes, that a head proper is found.
The cuttle-fishes have a remarkable cartilaginous box, which, like a skull, protects their anterior nervous ganglia and gives support to the muscles. The head of the vertebrated animals presents a regular series of increasing complexity from the lancelet upwards, and as the anterior nervous mass enlarges, and its ganglia increase in complexity, so do the anterior vertebra change their character; as the brain becomes specialized, so does the brain-case or skull, attaining its highest development in man.
In man, and in the higher vertebrates, the head consists of an upper chamber, lodging the brain, the eyes, and other sense organs, and a lower, lodging the first portion of the alimentarycanal. In proportion as the vertebrates become developed, the brain increases in size, and its position advances anteriorly, until, in man, it comes to overhang the face.
Head is the unit of measurement of cattle. Thus a herd of 100 cattle is referred to as 100 head.
The Alpine shrew (Sorex alpinus) is a uniformly dark coloured shrew, with pale feet and underside of the tail. The lower canine and premolars are clearly bicuspid; the 4th and 5th uni-cuspid teeth the same size. The tail is as long as the head and body. Alpine shrews are found in Alpine meadows and moors at altitudes from 200 to 3335 metres often in rocky habitats, frequenting the stony banks of mountain streams. The alpine shrew is a good climber, using its tail for balance and support. It feeds on snails, earthworms, spiders, isopods, chilopods, insects and insect larvae. The breeding season is from May to October, with two or three litters a year each averaging five or six young, but maybe as many as nine. Research Alpine Shrew
Avocet (Avoset) is the popular name for long-legged, web-footed shorebirds of the genus Recurvirostra, family Recurvirostridae order Charadriiformes. They are characterized by a long, slender, up-curved bill and frequent marshes where they search shallow water with their sensitive beaks for crustaceans, snails, and similar prey. There are four species of the genus: one found in Eurasia and Africa, one in North America, one in Australia, and one in South America. Avocets build simple nests on the ground in marshy places and usually lay four olive or buff coloured eggs, thickly spotted with dark brown. Research Avocet
The blackbird or merle (Turdus merula) is a British bird of the thrush family common in Britain and throughout Europe. It is larger than the common thrush, its length being about 25 cm. The male has black plumage and a yellow bill. The female is dark brown with a dark bill. The nest is usually in a thick bush, and is built of grass, roots, twigs, etc, strengthened with clay. The eggs, generally four or five in number, are of a greenish-blue, spotted with various shades of brown. The song is rich, mellow, and Mute-like, but of no great variety or compass.
Its food is insects, worms, snails, fruits, etc, and blackbirds may often be seen huntingworms across garden lawns which they do by attracting the worms to the surface by stamping their feet in imitation of rain fall, listening with their head cocked to one side, and then yanking the worm from the ground with their beak when it emerges.
The blackbird was formerly known as the 'Ouzel' or 'Ousel', 'missel thrush', 'mistletoe thrush', 'Holm Thrush', 'Holm Screech' and 'storm cock' in various parts of England, Scotland and Wales.
The blackbirds or crow-blackbirds of America are quite different from the European blackbird, and are more nearly allied to the starlings and crows.
The red-winged blackbird (Agelaius phoeniceus}, belonging to the starling family, is a familiar American bird that congregates in great flocks. Research Blackbird
The blindworm or slow-worm (Anguis fragilis) is a reptile, forming a connecting link between the lizards and the snakes, perfectly snake-like in form, having no appearance of external limbs, though the bones of the shoulders and pelvis exist in a rudimentary form. They are about 30 cm long, and of nearly equal thickness throughout. Its eyes, though brilliant, are small, and hence its common name. It is common in Great Britain, and is spread over almost the whole of Europe, Western Asia, and Northern Africa. It is perfectly harmless, living upon worms, insects, and snails, and hybernating during the winter. It receives its specific name of fragilis from the fact that when frightened it stiffens its muscles to such an extent, and becomes so rigid, that its tail may be snapped off by a slight blow. Research Blindworm
Cantharidae is the soldier beetle family of insects of the order Coleoptera. They are beetles with a rather thin and soft cuticle, so that the body and elytra are much less rigid than is usual for beetles. The members of the family generally eat other insects, but some eat young oak tree shoots. The larvae crawl about on the ground eating slugs and snails. Research Cantharidae
Cychrus is a genus of beetles of the family Carabidae, resembling the genusCarabus, but with a longer head. They feed on snails, earthworms and other small creatures by night, hiding under moss and loose bark during the day. The only British species is Cychrus caraboides living in damp woodlands at altitudes below 2000 metres and growing to between 12 and 20 mm in length. Research Cychrus
The Dahlia - named after the Swedish botanist Andrew Dahl - is a genus of perennial plants of the Compositae family native to Mexico, but introduced into Britain as a popular garden plant in 1789. Snails are very fond of the foliage of the Dahlia, and will often strip domestic plants of all their leaves. Research Dahlia
Dipsadinae is the 'American Snail-eating Snakes' subfamily of reptiles of the typical snakes family, Colubridae, suborder Serpentes (Snakes). The subfamily contains three genera and about 48 species found in South and Central America within rain forests and montane forests. The members vary in length from 25 to 90 cm, and are highly specialised with long front teeth which are used to extract snails from their shells. Research Dipsadinae
The Gasteropods (Gasteropoda), are a class of molluscs, consisting of animals inhabiting a univalve shell, although some of the group are wholly destitute of a shell. The shell is either a small internal plate, as in slugs; or cone-shaped and spiral, as in the majority; or multivalve, the pieces following each other along the middle line, as in the chitons. No known gasteropod has a bivalve shell. The distinguishing characteristic is the foot, which is broad, muscular, and disc-like, and attached to the ventral surface. The class is divided into two sub-classes, the Branchiata or Branchiogasteropoda, breathing water by gills, and the Pulmonata or Pulmogasteropoda, breathing air by a sort of lung apparatus. The former include whelks and periwinkles, etc; the latter include the ordinary land-snails, slugs, pond-snails, etc. Research Gasteropod
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Alpine Shrew
