The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " eVolution is the third Album by eLDee, it was due to be released in 2008 An adaptation is a characteristic of an Organism that has been favored by Natural selection and Most mouthparts represent modified, paired appendages, which in ancestral forms would have appeared more like legs than mouthparts. An appendage in the broadest sense is an additional or subsidiary part existing on or added to something which can generally still function if the appendage has never existed or In general, arthropods have mouthparts for cutting and chewing, piercing and sucking, siphoning, and filtering. This article outlines the basic elements of four arthropod groups: insects, myriapods, crustaceans and chelicerates. Insects are used as the model, with the novel mouthparts of the other groups introduced in turn. Insects are not, however, the ancestral form of the other arthropods discussed here. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint "

Insects

Insect mouthparts exhibit a range of forms. Insects ( Class Insecta) exhibit a range of mouthparts adapted to particular modes of feeding The earliest insects had chewing mouthparts. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Specialisation includes mouthparts modified for siphoning, piercing, sucking and sponging. These modifications have evolved a number of times. For example, mosquitoes (which are flies) and aphids (which are bugs) both pierce and suck, however female mosquitoes feed on animal blood whereas aphids feed on plant fluids. Mosquitoes are insects in the family Culicidae. They have a pair of scaled wings a pair of Halteres, a slender body and long legs This section provides an overview of the individual mouthparts of chewing insects.

Figure 1: Chewing mouthparts of a grasshopper. Legend: lr, labrum; md, mandibles; mx, maxillae; hp hypopharynx; lb, labium.

Labrum

The labrum is a flat extension of the head (below the clypeus), covering the mandibles. Unlike other mouthparts, the labrum is a single, fused plate (though it originally was — and embryonically is — two structures). It is the upper-most of the mouthparts and located on the midline. It serves to hold food in place during chewing by the mandibles and thus can simply be described as an upper lip.

Mandible

Chewing insects have two mandibles, one on each side of the head. They are typically the largest mouthpart of chewing insects, being used to masticate (cut, tear, crush, chew) food items. They open outwards (to the sides of the head) and come together medially.

Maxilla

Paired maxillae cut food and manipulate it during mastication. Maxillae can have hairs and “teeth” along their inner margins. At the outer margin, the galea is a cupped or scoop-like structure, which sits over the outer edge of the labium. They also have palps, which are used to sense the characteristics of potential foods.

Labium

The labium is a single structure, although it is formed from two fused secondary maxillae. It can be described as the floor of the mouth. With the maxillae, it assists manipulation of food during mastication.

Hypopharynx

The hypopharynx is a somewhat globular structure, arising from the base of the labium. It assists swallowing.

Myriapods

Figure 2: Ventral view of forcipules of a centipede, arising from the first body segment

Myriapods comprise four classes of arthropod, each with a similar morphology: Class Chilopoda (centipedes); Class Diplopoda (millipedes); Class Pauropoda; and Class Symphyla. Myriapoda is a Subphylum of Arthropods containing Millipedes Centipedes and others A class is the Taxonomic rank in the Biological classification of organisms in Biology below phylum and above order. The term morphology in Biology refers to the outward appearance ( Shape, Structure, Colour, Pattern) of an Organism Centipedes (from Latin prefix centi-, "hundred" and Greek ποδός podos, " Foot " are Millipedes (Class Diplopoda, previously also known as Chilognatha are Arthropods that have two pairs of legs per segment (except for the first segment behind Pauropods are small pale Centipede -like Arthropods. They form the order Pauropodina, belonging to the monotypic class Symphylans, also known as garden centipedes or glasshouse symphylans, are Soil -dwelling Arthropods of the class Symphyla Myriapod mouthparts are similar to those of chewing insects, although there is some variation between the myriapod classes. A labrum is present but sometimes is not obvious and forms an upper lip, often in association with an epistome. Stomotheca is the term applied to the feeding apparatus in front of the mouth of Harvestmen, and sometimes the related Scorpions Usually it consists of the epistome The labium is formed by first or second maxillae. The preoral cavity so-formed contains paired mandibles and a hypopharynx.

Forcipules

Centipedes, in addition to their mouthparts, possess a pair of "poison claws" or forcipules. Centipedes (from Latin prefix centi-, "hundred" and Greek ποδός podos, " Foot " are These, like the maxillipeds of crustaceans, are modified legs and not true mouthparts^[1]. The decapod Crustacean such as a crab lobster shrimp or prawn is made up of nineteen Body segments grouped into two main body parts the Cephalothorax The forcipules arise from the first body segment, curving forward and to the midline. The tip is a pointed fang, which has an opening from a venom gland. The forcipules are used to capture and poison prey.

Crustaceans

Crustaceans comprise a number of classes, with various feeding modes supported by a range of adaptions to the mouthparts. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting In general, however, crustaceans possess paired mandibles with opposing biting and grinding surfaces. The mandibles are followed by paired first and second maxillae. Both the mandibles and the maxillae have been variously modified in different crustacean groups for filter feeding with the use of setae.

Figure 3: The mouthparts of an edible crab: the third maxillipeds conceal the remaining mouthparts; the claws are not considered mouthparts. The edible crab, Cancer pagurus, is a species of Crab found in the North Sea, North Atlantic and the Mediterranean Sea A claw is a curved pointed appendage found at the end of a toe or finger in most Mammals, Birds, and some Reptiles.

Maxillipeds

Up to the first three pairs of legs are modified to maxillipeds, which assist manipulation of food items, by passing food forward to the mandibles for chewing or to the maxillae for cutting into smaller pieces. The decapod Crustacean such as a crab lobster shrimp or prawn is made up of nineteen Body segments grouped into two main body parts the Cephalothorax

Setae

Filter feeding crustaceans have setae on modified appendages that act as filters. Seta (plural setae) is a biological term derived from the Latin word for " Bristle " Filter feeding may have developed in association with swimming, with early morphological adaptions occurring on the appendages of the body trunk. Subsequent adaptions appear to have favoured forward filtering appendages. Filtering appendages generate water currents that bring food items into reach for collection by setae. Other setae may be used to brush the filtering setae clean, and yet other setae may transport food items to the mouth.

Cirri

Barnacles have thoracic appendages modified for feeding, the cirri, which filter suspended food particles from water currents and pass the food to the mouth. A barnacle is a type of Arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence distantly related to

Chelicerates

Chelicerates comprise four classes of arthropod, with similar gross morphology but defining differences: Class Xiphosura (horseshoe crabs); Class Eurypterida (the extinct eurypterids); Class Arachnida (spiders, scorpions, ticks and mite)s; and Class Pycnogonida (sea spiders). The subphylum Chelicerata constitutes one of the major subdivisions of the phylum Arthropoda including the Arachnids Horseshoe crabs and related forms A class is the Taxonomic rank in the Biological classification of organisms in Biology below phylum and above order. Xiphosura is a class of marine chelicerates which includes a large number of extinct lineages and only four recent species in the family Limulidae, which The horseshoe crab or Atlantic horseshoe crab ( Limulus polyphemus) is a marine Chelicerate Arthropod. The eurypterids (sea scorpions include the largest known Arthropod that ever lived (with the possible exception of Arthropleuridae) Spiders are Predatory Invertebrate Animals that have two body segments, eight legs no chewing mouth parts and no wings Scorpions are eight-legged Carnivorous Arthropods They are members of the order Scorpiones within the class Arachnida. Tick is the common name for the small Arachnids in Superfamily Ixodoidea that along with other Mites constitute the Acarina. Mites, along with Ticks belong to the subclass Acarina (also known as Acari and the class Arachnida Mites are among the most diverse and successful Sea spiders, also called Pantopoda or pycnogonids ('pycnogonid' = Greek for 'thick knee' are marine Arthropods of class Pycnogonida Chelicerates are in part defined by possessing chelicerate appendages, although crustaceans also possess chelate appendages. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Chelicerates are more easily distinguished from other arthropods in lacking antennae. Antennae (singular antenna) are paired Appendages connected to the front-most segments of Arthropods In Crustaceans they are

Figure 4: Types of chelicerae: 3-segmented chelate (in red), jackknife (in green) and scissor (in blue)

Chelicerae

Chelicerae are chelate appendages that are used to grasp food. The Chelicerae are mouth parts of the Chelicerata, an Arthropod Subphylum that includes Arachnids, Merostomata For example, in horseshoe crabs they are like pincers, where-as in spiders they are hollow and contain (or are connected to) venom glands, and are used to inject venom to disable prey prior to feeding. In some spiders, the chelicerae have teeth, which are used to macerate prey items to assist digestion by secreted enzymes. Those spiders without toothed chelicerae inject digestive enzymes directly into their prey. Mites and ticks have a range of chelicerae. Carnivores have chelicerae that tear and crush prey, where-as herbivores can have chelicerae that are modified for piercing and sucking (as do parasitic species). In sea spiders, the chelicerae (also known as chelifores) are short and chelate, and are positioned either side of the base of the proboscis or sometimes vestigial or absent.

Pedipalps

In addition to chelicerae, arachnids also possess a pair of pedipalps. Pedipalps, are the second pair of Appendages of the Prosoma in the subphylum Chelicerata. In scorpions, the pedipalps are large and chelate (of the scissor type at Figure 4). They are used to capture and hold prey items for stinging before the chelicerae tear the prey into items for digestion. In spiders, the pedipalps of males are modified and function as secondary sex organs (transmission of sperm to the female). The pedipalps of mites and ticks vary depending on the species’ feeding mode. They are segmented and may be leg-like or chelate, like a second pair of chelicerae.

Proboscis

Sea spiders possess a tubular proboscis forward from the body trunk, at the end of which is the opening to the mouth. In those species that lack chelifores and palps, the proboscis is well developed and more mobile and flexible. In such cases it can be equipped with sensory bristles and strong rasping ridges around the mouth.

References

1. ^ Rowland Shelley & Paul Marek (2005-03-01). Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant Centipedes: general information. East Carolina University. East Carolina University is a public, Coeducational, Doctoral / Research University located in Greenville, North