With very few exceptions the abdomen is without locomotor limbs.
18, 21 b); the body shortened, with the abdomen swollen, but protected with tubercles and spines, and with longish legs adapted for an active life, as in the predaceous larvae of ladybirds; the body soft-skinned, swollen and caterpillar-like, with legs well developed, but leading a sluggish underground life, as in the grub of a chafer; the body soft-skinned and whitish, and the legs greatly reduced in size, as in the wood-feeding grub of a longhorn beetle.
When Hydrophilus dives it carries a supply of air between the elytra and the dorsal surface of the abdomen, while air is FIG.
Among the burrowing and tubicolous forms it is not uncommon for the body to be distinguishable into two or more regions; a "thorax," for example, is sharply marked off from an "abdomen" in the Sabellids.
Ten segments are recognizable in the abdomen, which is elongated and tapers at the hinder end.
A true insect, or member of the class Hexapoda, may be known by the grouping of its body-segments in three distinct regions - a head, a thorax and an abdomen - each of which consists of a definite number of segments.
He was taller than average, over six and a half feet, built like a rock with wide shoulders and tapered abdomen and hips beneath a jumpsuit similar to those worn by the prisoners.
Ten segments can be distinguished in the tapering abdomen, the ninth frequently bearing a pair of tail-feelers (cerci), and the tenth, attached ventrally to the ninth, having the anal opening at its extremity and performing the function of a posterior limb, supporting and temporarily fixing the tail end of the insect on the surface over which it crawls.
24), insects with rather soft cuticle, the elytra (often abbreviated) not fitting closely to the sides of the abdomen, the head constricted behind the eyes to form FIG.
Ing the dorsal with the ventral sclerites of the Lateral thoracic abdomen, lessens t he capacity of the abdo ternal femoral minal region, while the contraction of the power Longit.
The impregnated female jigger burrows into the feet of men and dogs, and becomes distended with eggs until its abdomen attains the size and appearance of a small pea.
It is the well-known peculiarity of this order that the female has a pouch or fold of skin upon her abdomen, in which she can place the young for suckling within reach of her teats.
In a large number of beetles of different families, stridulating areas occur on various segments of the abdomen, and are scraped by the elytra.
These segments are very mobile, and as the rove-beetles run along they often curl the abdomen upwards and forwards like the tail of a scorpion.
Such larvae, and also many with soft cuticle and swollen abdomen - those of the notorious "Colorado beetle," for example - feed openly FIG.
The morphology of the abdomen, ovipositor and genital armature is dealt with by K.
In the more generalized insects the abdomen evidently consists of ten segments, the hindmost of which often carries a pair of tail-feelers, (cerci or cercopods) and a terminal anal segment.
Moreover, in this order the abdomen shows at first a division into only nine segments and a terminal mass, which last subsequently becomes divided into two.
The appendages of the abdomen are called cerci, stylets and gonapophyses.
In the adult state no insect possesses more than six legs, and they are always attached to the thorax; in many Thysanura there are, however, processes on the abdomen that, as to their position, are similar to legs.
In the embryos of many insects there are projections from the segments of the abdomen similar, to a considerable extent, to the rudimentary thoracic legs.
The pseudopods that exist on the abdomen of numerous caterpillars may possibly arise from the embryonic pseudopods, but this also is far from being established.
- Cross sections through Abdomen of German Cockroach Embryo.
A gnat pupa swims through the water by powerful strokes of its abdomen, while the caddis-fly pupa, in preparation for its final ecdysis, bites its way out of its subaqueous protective case and rises through the water, so that the fly may emerge into the air.
Symphyta: Abdomen not basally constricted.
A pocrita : Abdomen markedly constricted at second segment.
In most respects, the shortened abdomen, for example, they are more specialized than the Thysanura, and most of the features in which they appear to be simple, such as the absence of a tracheal system and of compound eyes, can be explained as the result of degradation.
Abdomen and Appendages.
Lastly, the males of some species of spiders differ from the females in possessing stridulating organs consisting of horny ridges and spikes and lodged either between the mandible and palpus as in some species allied to Linyphia, one of the Argyopidae, or between the cephalo-thorax and abdomen as in Steatoda, one of the Theridiidae and Cambridgea, one of the Agalenidae.
The abdomen is oval, sandy-grey in hue and beset with warts and bristles; the prothorax forms a mobile neck for the large square head, which carries a pair of long and powerful toothed mandibles.
The glands occur in groups, and lead into common ducts which open usually so much reduced that the foremost apparent ventral sclerite of the abdomen represents the third sternite.