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". 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-formati ...

– 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, ...

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 p ...

* hamulus of hamate bone *

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 canal ...

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 Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...

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 Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

of aphids 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 the ...

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 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 Latin ...

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

Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...

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 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 ...

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

Burdock ''Arctium'' is a genus of biennial plants commonly known as burdock, family Asteraceae. Native to Europe and Asia, several species have been widely introduced worldwide. Burdock's clinging properties, in addition to providing an excellent mecha ...

s, well known as the alleged inspiration for Velcro.

References

{{Reflist Insect anatomy Botany Skeletal system