Morphology

Morphology, broadly defined as the study of animal form, is a field that helps us understand animal diversity and animal history. For centuries, scientists have been interested in how animals are put together and how the parts work together to make functioning organisms that can run, fly, swim, eat, and survive. Early scientific efforts focused on descriptive methods in which scientists dissected specimens and described the musculoskeletal and other body systems with words and detailed drawings.

As new techniques were developed, scientists began to specialize along the lines of various subdisciplines, including functional morphology and ecological morphology. Morphologists moved beyond what had started as a purely descriptive science and began to ask and answer more complex questions.

Functional morphology emphasizes the mechanics of a particular structure—how it works. For example, a functional morphologist might examine the pattern of musculoskeletal activity involved in an activity such as running. Using techniques such as high-speed video, X-ray video, force-platform measurements, and EMGs (electromyographs, or recordings of electrical activity in muscles), the scientist can determine a joint's range of motion, the duration and intensity of muscle activity, and the order in which the muscles activate to produce a pattern of movement.

Functional morphologists are often interested in the performance limits of a particular system. They ask questions such as: How much force can the human jaw produce? How fast can a lizard sprint on an inclined surface? How much weight can a thigh bone stand before it breaks?

Ecological morphology (also called "ecomorphology") considers the structure of an organism in the context of its habitat and ecological role. Ecological morphologists are more interested in how structures are actually used in nature than in the limits to which structures can be pushed in an artificial laboratory setting. Ecological morphologists distinguish between a structure's biological role and its function. Therefore, they usually spend some time familiarizing themselves with the habits and natural surroundings.

Ecological morphologists ask questions such as: How does the shape of a hawk's beak help it tear through the flesh of its prey? How does the shape of fish larvae help them disperse along wave-swept shores? How does the shape of a bat's wing help it maneuver while catching insects at night?

Although these specific research areas are worthy of pursuit in and of themselves, many scientists promote an integrative approach to the study of morphology that brings together these and other aspects of morphological research. Evolutionary morphology draws lessons from functional and ecological morphology to determine how structures evolved. Using a comparative method, morphologists put structures into a historical context and draw conclusions about how a structure came to exist based on structural and/or functional similarities and differences between related animals.

When variations in environmental pressures and biological roles are taken into account, morphological differences can lend insight into the origin of animal diversity. As animals evolve over time, their morphology adapts to specific selective pressures such as prey type and abundance, predator type and abundance, climate , and habitat characteristics. The diversity of animal form reflects the complex interactions between animals and their environment.

see also Adaptation; Morphological Evolution in Whales.

Judy P. Sheen

Bibliography

Kardong, Karl V. Vertebrates: Comparative Anatomy, Function, Evolution. Boston: Mc-Graw Hill, 1998.

Wainwright, Peter C., and Steve M. Reilly, eds. Ecological Morphology: Integrative Organismal Biology. Chicago: University of Chicago Press, 1994.

mor·phol·o·gy / môrˈfäləjē/ • n. (pl. -gies) the study of the forms of things, in particular: ∎  Biol. the branch of biology that deals with the form of living organisms, and with relationships between their structures. ∎  Linguistics the study of the forms of words.DERIVATIVES: mor·pho·log·ic / ˌmôrfəˈläjik/ adj.mor·pho·log·i·cal / ˌmôrfəˈläjikəl/ adj.mor·pho·log·i·cal·ly / ˌmôrfəˈläjik(ə)lē/ adv.mor·phol·o·gist / -jist/ n.

MORPHOLOGY. In LINGUISTICS, the study of the structure of words, as opposed to SYNTAX, the study of the arrangement of words in the higher units of phrases, clauses, and sentences. The two major branches are inflectional morphology (the study of inflections) and lexical morphology (the study of WORD-FORMATION). See ACCIDENCE, INFLECTION, LINGUISTIC TYPOLOGY, MORPHEME.

morphological system In geomorphology, a theoretical construct consisting of the relationship between the physical properties of a natural system (geomorphological). For example, the physical dimensions of a beach (angle of slope seaward, average grain size, porosity, and moisture content) may be related to each other in an orderly manner, and so constitute a morphological system, and the geometric properties of a valley-side slope are typically correlated with certain characteristics of soil and vegetation.

morphological system In geomorphology, a theoretical construct consisting of the relationship between the physical properties of a natural (geomorphological) system. For example, the physical dimensions of a beach (angle of slope seaward, average grain size, and porosity) may be related to each other in an orderly manner, and so constitute a morphological system, and the geometric properties of a valley-side slope are typically correlated with certain characteristics of soil and vegetation.