Samiksha Jaiswal

Entognatha

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Kingdom  Animalia
Subphylum  Hexapoda
Higher classification  Hexapoda
Phylum  Arthropoda
Scientific name  Entognatha
Rank  Class
Entognatha Image Gallery of Entognatha
Lower classifications  Springtail, Diplura, Protura

An introduction to arthropods presentation 4 entognatha apterygota and paleoptera


The Entognatha are a class of wingless (ametabolous) arthropods, which, together with the insects, makes up the subphylum Hexapoda. Their mouthparts are entognathous, meaning that they are retracted within the head. Entognatha are apterous, meaning that they lack wings. The class contains three orders: Collembola (springtails), Diplura and Protura. These three groups were historically united with the order Thysanura to form the class Apterygota, but it has since been recognized that the hexapodous condition of these animals has evolved independently from that of insects, and independently within each order. The orders may not be closely related, in which case Entognatha would be a polyphyletic group.

Contents

Entognatha Image Gallery of Entognatha

Morphology

Entognatha Entognatha

These minute arthropods are apterous, unlike some orders of insects that have lost their wings secondarily (but are derived from winged ancestors). Their mouthparts are enclosed within a pouch in the head capsule, called the gnathal pouch, so only the tips of the mandibles and maxillae are exposed beyond the cavity. This pouch is created in the embryo by a flap or lateral head sclerite near the mouth on each side of the head which fuses with the labium. Other differences with insects are that each antennal segment is musculated; in insects, only the two basal segments are. Sperm transfer is always indirect, and there is an ovipositor in the females. Of the three orders, only collembolans possess eyes; nevertheless, many collembolans are blind, and even when compound eyes are present, there are no more than eight ommatidia.

Entognatha Image Gallery of Entognatha
  • Collembolans have a ventral tube termed a collophore on the first abdominal segment. The collophore is involved in moisture absorption. On the third abdominal segment is the retinaculum that holds the furcula. The furcula is the "spring" for which the Collembola are given the name springtails.
  • Proturans, sometimes referred to as "coneheads", do not have eyes or antennae. They possess abdominal styli thought to be vestigial legs.
  • Diplurans have a pair of caudal cerci, from which their name, meaning "two-tailed", is derived. They also possess abdominal styli.

  • Entognatha Entognatha Entomology 4161 with Brahnam at University of Florida
    Entognatha httpsuploadwikimediaorgwikipediacommonsthu
    Entognatha Entognatha Entomology 4161 with Brahnam at University of Florida

    References

    Entognatha Wikipedia


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