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 ...

, 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 A diminutive is a root word that has been modified to convey a slighter degree of its root meaning, either to convey the smallness of the object or quality named, or to convey a sense of intimacy or endearment. A ( abbreviated ) is a word-form ...

– 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 taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...

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 * hamulus of hamate bone * lacrimal hamulus

Arthropoda

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

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 Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

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 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 ...

s and

scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than th ...

s. 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 Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

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 Thorax, ...

, the underside of the third

abdominal segment The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the tor ...

bears a hooked structure, variously called the retinaculum 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 co ...

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

Botany

botany Botany, also called plant science (or plant sciences), 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 "bot ...

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

rachilla Rachilla may refer to the following topics in botany: * Rachilla (floral axis) A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other Monocots. Each spikelet has one or more florets. The spikele ...

of Uncinia, 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