A hamus or hamulus is a structure functioning as, or in the form of, hooks or hooklets.

Etymology

The terms are directly from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

, in which ''hamus'' means "

hook A hook is a tool consisting of a length of material, typically metal, that contains a portion that is curved or indented, such that it can be used to grab onto, connect, or otherwise attach itself onto another object. In a number of uses, one e ...

". The plural is ''hami''. ''Hamulus'' is the diminutive – hooklet or little hook. The plural is ''hamuli''. Adjectives are ''hamate'' and ''hamulate'', as in "a hamulate wing-coupling", in which the wings of certain insects in flight are joined by hooking hamuli on one wing into folds on a matching wing. ''Hamulate'' can also mean "having hamuli". The terms ''hamose'', ''hamular'', ''hamous'' and ''hamiform'' also have been used to mean "hooked", or "hook-shaped". Terms such as ''hamate'' that do not indicate a diminutive usually refer particularly to a hook at the tip, whereas diminutive terms such as ''hamulose'' tend to imply that something is beset with small hooks.

Anatomy

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

anatomy, a hamulus is a small, hook-shaped portion of a bone, or possibly of other hard tissue. In human anatomy, examples include: *

pterygoid hamulus The pterygoid hamulus is a hook-like process at the lower extremity of the medial pterygoid plate of the sphenoid bone of the skull. It is the superior origin of the pterygomandibular raphe, and the levator veli palatini muscle. Structure The ...

hamulus of hamate bone The hamate bone (from Latin hamatus, "hooked"), or unciform bone (from Latin ''uncus'', "hook"), Latin os hamatum and occasionally abbreviated as just hamatum, is a bone in the human wrist readily distinguishable by its wedge shape and a hook-l ...

lacrimal hamulus The lacrimal hamulus is a small, hook-like bony projection of the lacrimal bone. It is a continuation of the posterior lacrimal crest. It articulates with the lacrimal tubercle of the maxilla, and completes the upper orifice of the lacrimal can ...

Arthropoda

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

morphology hamuli are hooklets, usually in the form of projections of the surface of the

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

. Hami might be actual evaginations of the whole thickness of the exoskeleton. The best-known examples are probably the row of hamuli on the anterior edge of the metathoracic (rear) wings of Hymenoptera such as the honeybee. The hooks attach to a fold on the posterior edge of the mesothoracic (front) wings. It is less widely realised that similar hamuli, though usually fewer, are used in wing coupling in the

Sternorrhyncha The Sternorrhyncha suborder of the Hemiptera contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the now-obsolete order "Homoptera". "Sternorrhyncha" refers to the rearward position of the mouthparts re ...

, the suborder of

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s and scale insects. In the Sternorrhyncha such wing coupling occurs particularly in the males of some species. The rear wings of that suborder frequently are reduced or absent, and in many species the last vestige of the rear wing to persist is a futile little strap holding the hamuli, still hooking into the fold of the large front wings. In those Springtails (Collembola) that have a functional

furcula The (Latin for "little fork") or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two pink clavicles. In birds, its primary function is in the strengthening of the thoracic ...

, the underside of the third abdominal segment bears a hooked structure, variously called the

retinaculum A retinaculum (plural ''retinacula'') is a band of thickened deep fascia around tendons that holds them in place. It is not part of any muscle. Its function is mostly to stabilize a tendon. The term retinaculum is New Latin, derived from the Lati ...

or hamula. It holds the furcula ready for release in times of emergency. The terms also are used in descriptive anatomy of some insect genitalia, such as hamuli in various

Odonata Odonata is an order of flying insects that includes the dragonflies and damselflies. Members of the group first appeared during the Triassic, though members of their total group, Odonatoptera, first appeared in Late Carboniferous. The two com ...

and "hamus" for the hooked part of the uncus in male Lepidoptera.

Botany

botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...

such words largely refer to hooked bristles such as the hooks on the rachilla of

Uncinia ''Uncinia'' is a genus of flowering plants in the family Cyperaceae, known as hook-sedges in Australia and as hook grasses or bastard grasses in New Zealand. The genus is characterised by the presence of a long hook formed by an extension of the ...

, which attach the fruit to passing animals, or the similarly functioning hooks on Burdocks, well known as the alleged inspiration for

Velcro Velcro, officially known as Velcro IP Holdings LLC and trading as Velcro Companies, is a British privately held company, founded by Swiss electrical engineer George de Mestral in the 1950s. It is the original manufacturer of hook-and-loop fast ...

References

{{Reflist Insect anatomy Botany Skeletal system