Epicoelia is a term used in zoology to describe a condition where the center of a biconvex vertebral body is deeper than the periphery. The spelling of the word can be explained using the International Phonetic Alphabet (IPA) transcription as ɛpɪkoʊliə. The first syllable, "epi," is pronounced as "eh-pee," while the second syllable "coelia" is pronounced as "koh-lee-uh". The stress falls on the second syllable, "coelia", which is pronounced with a schwa sound followed by "lee-uh."
Epicoelia refers to a condition or abnormality found in the fossil record of certain marine invertebrates, particularly corals. It is characterized by a symmetrical arrangement of the septa (thin partitions) within the corallites, the skeletal structures that house the coral polyps. This condition leads to a uniformity in the size, shape, and placement of the septa within each individual corallite.
In corals, septa play a crucial role in maintaining the structural integrity of the coral skeleton and providing support to the colonial growth form. Normally, the septa exhibit some degree of variation, both in size and arrangement, within and among corallites.
The presence of epicoelia represents a departure from this normal variation. In epicoelic corals, all the septa of a corallite are more or less identical in size, shape, and spacing. They radiate symmetrically from the central axis of the corallite, creating a star-like pattern. This consistent and radial arrangement of septa is distinctly different from the irregular, non-symmetrical septa formation found in most corals.
Epicoelia is considered an important diagnostic feature in the identification and classification of certain fossil coral species. Its presence or absence can help distinguish different genera and species, aiding paleontologists in understanding the evolutionary relationships and diversity of ancient corals. Additionally, the study of epicoelia can provide insights into the environmental and ecological conditions under which these corals thrived in the past.
The word "epicoelia" has Greek origins. It is derived from the combination of two Greek words: "epi" meaning "upon" or "above", and "koilos" meaning "hollow" or "cavity". Therefore, "epicoelia" can be translated roughly as "upon a hollow" or "above a cavity". This etymology reflects the meaning of the word, as "epicoelia" is a medical term used to describe a condition where there is a fluid-filled cavity (usually in an embryo) surrounded by a layer of tissue.