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

The Chelicerae are mouth parts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata (horseshoe crabs), and Pycnogonida (sea spiders). Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have. Additionally, some chelicerae, such as those found in spiders, are hollow and contain (or are connected to) venom glands, and are used to inject venom into prey or a (perceived) threat. Image File history File links Queliceras. ... Image File history File links Queliceras. ... Classes Arachnida- spiders, scorpions, etc. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... In biology, a subphylum is a taxonomic rank intermediate between phylum and superclass. ... Orders Acarina Amblypygi Araneae Opiliones Palpigradi Pseudoscorpionida Ricinulei Schizomida Scorpiones Solifugae Uropygi The arachnids, Arachnida, are a class of invertebrate animals in the subphylum Chelicerata. ... Orders †Order Eurypterida Order Xiphosura Merostomata is a class of marine arthropods which includes horseshoe crabs and eurypterids. ... Binomial name Limulus polyphemus The horseshoe crab (Limulus polyphemus) also known as King Crab, is an arthropod that is more closely related to spiders than crabs. ... Families may not be a complete list: Ammotheidae Austrodecidae Callipallenidae Colossendeidae Nymphonidae Phoxichilidiidae Pycnogonidae Rhynchothoracidae Endeididae Sea spiders, also called Pantopoda or pycnogonids, are marine arthropods of class Pycnogonida. ... Families may not be a complete list: Ammotheidae Austrodecidae Callipallenidae Colossendeidae Nymphonidae Phoxichilidiidae Pycnogonidae Rhynchothoracidae Endeididae Sea spiders, also called Pantopoda or pycnogonids, are marine arthropods of class Pycnogonida. ... Diversity 111 families, 40,000 species Suborders Mesothelae Mygalomorphae Araneomorphae  See table of families Closeup image of a Wolf Spider Wikispecies has information related to: Spiders Spiders are predatory invertebrate animals with two body segments, eight legs, no chewing mouth parts and no wings. ... Wasp stinger, with droplet of venom Venom or zootoxin (literally, animal poison) is any of a variety of poisons used by several groups of animal species, for the purpose of defense and hunting prey. ...

Types of chelicera

The chelicerae can be divided in three kinds: jackknife chelicera (green in the image to the right), scissor chelicera (blue) and 3-segmented chelate chelicerae (red).

Jacknife chelicera

Phidippus audax, jumping spider:The basal parts of the chelicerae are the two irridescent green mouthparts.

The jacknife chelicera is subchelate (with fixed finger much reduced or absent) and is composed of two segments. This type of chelicera occurs exclusively in the Tetrapulmonata. Image File history File linksMetadata Phidippus_audax3. ... Image File history File linksMetadata Phidippus_audax3. ... Phidippus is a genus of the family of jumping spiders or Salticidae, some species of this group are characterized by being some of the largest jumping spiders, many species also present irridescent green chelicerae or mouth parts. ... Diversity 553 genera, 5025 species Genera See List of Salticidae genera Wikispecies has information related to: Salticidae The jumping spiders (family Salticidae) contains more than 500 described genera and over 5,000 species, making it the largest family of spiders with about 13% of all species. ... Tetrapulmonata Shultz, 1990 is a non-ranked supra-ordinal group of arachnids. ...

Jacknife chelicera presents two different forms: orthognathous and labidognathous. The orthognathous chelicera is articulated in a manner that enables movements of the appendages parallel to the body axis. This kind of chelicera occurs in the Liphistiomorphae and Mygalomorphae spiders and in the related orders Amblypygi, Schizomida, Thelyphonida. The labidognathous chelicera moves at right angles to the body axis. This kind of chelicera is rotationed and occurs exclusively in the Araneomorphae spiders. Families Antrodiaetidae (folding trapdoor spider) Atypidae (atypical tarantula) Ctenizidae (trapdoor spider) Cyrtaucheniidae (wafer trapdoor spider) Dipluridae (funnel-web tarantula) Hexathelidae (venomous funnel-web tarantula) Mecicobothriidae (dwarf tarantulas) Theraphosidae (tarantula) The Mygalomorphae, (also called the Orthognatha), are an infraorder of spiders. ... An amblypygid is an invertebrate animal belonging to the order Amblypygi in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. ... Families Calcitronidae † Petrunkevitch, 1945b Hubbardiidae Cook, 1899 Protoschizomidae Rowland, 1975 A schizomid is an invertebrate animal belonging to the order Schizomida in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. ... Families Geralinuridae Thelyphonidae A uropygid, commonly known as a whip scorpion, is an invertebrate animal belonging to the former order Uropygi in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. ... The Araneomorphae, previously called the Labidognatha, are a suborder of spiders. ...

Spider chelicerae

Spider chelicerae. The chelicerae are shown in black, the surface of the cephalothorax in brown, the legs in reddish brown, and the poison glands and surrounding muscle tissue in green. The fang portion of the right chelicerae can be seen projecting into the space between the two chelicerae.

The chelicerae consist of a base segment that articulates with the cephalothorax and a fang portion that articulates with the base segment. An analogy for this is a two-segment finger, the outer segment of which consists of a hollow fang. Except for a few small families of spiders, all spiders have venom that is injected into their prey through openings in the tips of their fangs when a spider bites something. The glands that produce this poison are located in the two segments of the chelicerae, and, in most spiders, extend beyond the chelicerae and into the cephalothorax. Image File history File links Spider_chelicerae. ... Image File history File links Spider_chelicerae. ... The cephalothorax is an anatomical term used of arachnid and malacostracan arthropods for the first major body section. ... Fang may mean: Fang (Harry Potter), a pet of Hagrid in the Harry Potter series Fang (band), a California punk band The Fang people of Central Africa A canine tooth A common Chinese surname (方), and less common ones (防,房 etc. ... Chelicerae of a black wishbone (Nemesiidae) spider, a mygalomorph Spiders are widely known, and feared by some, for their capability of biting human beings. ...

The fang, the organic functional equivalent to a hypodermic needle is what penetrates the skin, fur, or exoskeleton of the spider's target--spider mouthparts are primarily intended for envenoming a spider's prey in most species, typically insects and other small arthropods; not for biting humans. The basal portion includes all or part of the spider's venom glands, which can be squeezed under voluntary control by the spider to force venom out of the glands and into the wound.^[1] Different bevels on hypodermic needles Syringe on left, hypodermic needle with attached color-coded luer lock on right. ... Orders See taxonomy Insects are invertebrates that are taxonomically referred to as the class Insecta. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ...

Side view of the cephalothorax of the spider in brown (with the legs removed) and the two portions of the chelicera.

When a spider bites, the two parts of the chelicerae come together like a folding knife, and when making a threat display or actually preparing to bite, the spider will open the angle of the fangs with the basal portion of chelicerae and also open the angle of the basal portion with the cephalothorax. In the tarantulas and other Mygalomorphae, the horizontal separation of the tips of the fangs does not change much, but in the other spiders the tips of the fangs move apart from each other as well as elevating. Even the tips of the fangs of the rather large spider shown above are quite sharp, and the spider's body is well adapted to driving the fangs into flesh. Some spider bites, such as those of the Sydney funnel-web spider, are reported to have penetrated toe nails and soft leather shoes. Image File history File links Spider_chelicerae2. ... Image File history File links Spider_chelicerae2. ... Families Antrodiaetidae (folding trapdoor spider) Atypidae (atypical tarantula) Ctenizidae (trapdoor spider) Cyrtaucheniidae (wafer trapdoor spider) Dipluridae (funnel-web tarantula) Hexathelidae (venomous funnel-web tarantula) Mecicobothriidae (dwarf tarantulas) Theraphosidae (tarantula) The Mygalomorphae, (also called the Orthognatha), are an infraorder of spiders. ... Binomial name Atrax robustus Pickard-Cambridge, 1877 The Sydney funnel-web spider, also called a funnel-web tarantula, (Atrax robustus) is regarded by some to be the most dangerous spider in the world. ...

The fang of this immature Psalmopoeus cambridgei spider is about 2mm long. The spider herself is about 25mm long

10x microphotograph of the chelicera and the tip of the smallest sewing needle available in ordinary commerce

10x microphotograph of the same Psalmopoeus cambridgei spider and the tip of the finest hypodermic needle available for farm use

Image File history File linksMetadata Psalmopoeus_cambridgei_Fang_60x. ... Image File history File linksMetadata Psalmopoeus_cambridgei_Fang_60x. ... Image File history File linksMetadata Psalmopoeus_cambridgei_Fang_&_sewing_needle. ... Image File history File linksMetadata Psalmopoeus_cambridgei_Fang_&_sewing_needle. ... Image File history File linksMetadata Psalmopoeus_cambridgei_Fang_and_hypo. ... Image File history File linksMetadata Psalmopoeus_cambridgei_Fang_and_hypo. ...

Scissor chelicera

The scissor chelicera is chelate and composed of two segments and occurs in the orders Pseudoscorpiones and Solifugae. Superfamilies Chthonioidea Neobisioidea Garypoidea Cheiridioidea Feaelloidea Cheliferoidea A pseudoscorpion, (also known as a false scorpion or book scorpion), is an arachnid belonging to the order Pseudoscorpionida, also known as Pseudoscorpiones or Chelonethida. ... The order Solifugae is a group of arachnids, containing around 900 species. ...

3-segmented chelate chelicerae

This is the primitive condition and occurs in arachnids such as the Scorpiones and the Opiliones. It also occurs in non-arachnid Chelicerata such as the Xiphosura and Eurypterida. Arguably the chelifores of the Pycnogonida are homologous to the chelicerae and should be included in this count. Orders Acarina Amblypygi Araneae Opiliones Palpigradi Pseudoscorpionida Ricinulei Schizomida Scorpiones Solifugae Uropygi The arachnids, Arachnida, are a class of invertebrate animals in the subphylum Chelicerata. ... A scorpion is an invertebrate animal with eight legs belonging to the order Scorpiones in the class Arachnida. ... The Phalangids (legacy name) or Opiliones (better known as harvestmen) are eight-legged invertebrate animals belonging to the order Opiliones in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. ... Classes Arachnida- spiders, scorpions, etc. ... Orders see text Merostomata is a class of marine arthropods which includes horseshoe crabs and eurypterids. ... Orders many, all extinct The eurypterids were the largest known arthropods that ever lived. ... Families may not be a complete list: Ammotheidae Austrodecidae Callipallenidae Colossendeidae Nymphonidae Phoxichilidiidae Pycnogonidae Rhynchothoracidae Endeididae Sea spiders, also called Pantopoda or pycnogonids, are marine arthropods of class Pycnogonida. ...

References

1. ^ Foelix, Rainer F. (1996). Biology of Spiders (2nd edition). Oxford University Press. ISBN ISBN 0-19-509594-4.