Femoral pores are a part of a

holocrine Holocrine (from Ancient Greek ὅλος; ''hólos'', “whole, entire” + κρῑ́νω; ''krī́nō'', “to separate”) is a term used to classify the mode of secretion in exocrine glands in the study of histology. Holocrine secretions are p ...

secretory gland Exocrine glands are glands that secrete substances on to an epithelial surface by way of a duct. Examples of exocrine glands include sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate and mucous. Exocrine glands are one of two ...

found on the inside of the thighs of certain

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

s and

amphisbaenian Amphisbaenia (called amphisbaenians or worm lizards) is a group of usually legless squamates, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As ...

s which releases

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s to attract mates or mark territory. In certain species only the male has these pores and in other species, both sexes have them, with the male's being larger. Femoral pores appear as a series of pits or holes within a row of scales on the ventral portion of the animal's thigh. Femoral pores are present in all

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

in the families

Cordylidae Cordylidae is a family of small- to medium-sized lizards that occur in southern and eastern Africa. They are commonly known as girdled lizards, spinytail lizards, or girdle-tail lizards. Cordylidae is closely related to the family Gerrhosauridae ...

Crotaphytidae The Crotaphytidae, or collared lizards, are a family of desert-dwelling reptiles native to the Southwestern United States and northern Mexico. Alternatively they are recognized as a subfamily, Crotaphytinae, within the clade Pleurodonta. They are ...

Hoplocercidae Hoplocercidae are a family of lizards native to the tropical forests, woodlands and savanna-like habitats of Central and South America. Alternatively they are recognized as a subfamily, Hoplocercinae. 20 species in three genera are described. Sp ...

Iguanidae The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana. Taxonomy Iguanidae is thought to be the sister group to the collared lizards (family Crotaph ...

Phrynosomatidae The Phrynosomatidae are a diverse family of lizards, sometimes classified as a subfamily (Phrynosomatinae), found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny ...

, and Xantusiidae. They are absent in all genera in the

Anguidae Anguidae refers to a large and diverse family of lizards native to the Northern Hemisphere. Common characteristics of this group include a reduced supratemporal arch, striations on the medial faces of tooth crowns, osteoderms, and a lateral fold ...

, Chamaeleonidae,

Dibamidae Dibamidae or blind skinks is a family of lizards characterized by their elongated cylindrical body and an apparent lack of limbs. Female dibamids are entirely limbless and the males retain small flap-like hind limbs, which they use to grip their ...

Helodermatidae The Helodermatidae or beaded lizards are a small family of lizards endemic to North America today, but formerly more widespread in the ancient past. Traditionally, the Gila monster and the Mexican beaded lizard were the only species recognized, ...

, Scincidae,

Xenosauridae Xenosauridae is a family of anguimorph lizards whose only living representative is the genus ''Xenosaurus'', which is native to Central America. Xenosauridae also includes the extinct genera '' Exostinus'' and '' Restes''. Also known as knob-scal ...

, and

Varanidae The Varanidae are a family of lizards in the superfamily Varanoidea within the Anguimorpha group. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely rel ...

families. They are present in other lizards and amphisbaenians quite variably, some geckoes, ''

Phelsuma ''Phelsuma'' is a large genus of geckos in the family Gekkonidae. Species in the genus ''Phelsuma'' are commonly referred to as day geckos. Some day geckos are seriously endangered and some are common, but all ''Phelsuma'' species are CITES App ...

'', for example have these pores, others in the same family do not. Femoralporewax

In the

desert iguana The desert iguana (''Dipsosaurus dorsalis'') is an iguana species found in the Sonoran and Mojave Deserts of the Southwestern United States and northwestern Mexico, as well as on several Gulf of California islands. Taxonomy The species was ...

(''Dipsosaurus dorsalis''), the waxy

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

s released from the femoral pores absorb

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

(UV) wavelengths making them visible to species which can detect UV light. According to tests performed on the Green iguana, the variation in the chemicals released by the femoral pores can help to determine age, sex, and individual identity of the animal in question. Male

leopard gecko The leopard gecko or common leopard gecko (''Eublepharis macularius'') is a ground-dwelling lizard native to the rocky dry grassland and desert regions of Afghanistan, Iran, Pakistan, India, and Nepal. The leopard gecko has become a popular pet, ...

s (''Eublepharis macularius''), actually taste the secretions by flicking their tongues, if a male determines the other gecko in question is a male, the two will fight. In certain species such as geckoes, the females lack femoral pores altogether. In most families of lizards that have femoral pores, notably the iguanids, both sexes have femoral pores, but the males tend to be much larger than females of the same size and age. In these instances they are used as a marker for

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. The number of femoral pores varies considerably among species. For example, the number of pores in male lizards of the family Lacertidae can range between zero (e.g. ''

Meroles anchietae The shovel-snouted lizard (''Meroles anchietae''), also known commonly as Anchieta's desert lizard, Anchieta's dune lizard and the Namib sand-diver, is a species of lizard in the family Lacertidae. The species is native to southern Africa. Et ...

'') and 32 (e.g. ''

Gallotia galloti ''Gallotia galloti'' (Gallot's lizard, Tenerife lizard, or Western Canaries lizard) is a species of Lacertidae, lacertid (wall lizard) in the genus ''Gallotia''. The species is found on the Canary Islands of Tenerife and La Palma. Both the Gen ...

'') per limb. Also, shrub-climbing species tend to have fewer femoral pores than species inhabiting other substrates (such as sandy and rocky substrate), suggesting a role of the environment on the evolution of the chemical signaling apparatus in lacertid lizards.

References

{{reflist Reptile anatomy