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A beetle leg. An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface appendages.
[8] [9] Microtentacles are cell protrusions attached to free-floating cells, associated with the spread of some cancer cells. [10] In prokaryotes such protrusions are known as surface or cell-surface appendages and include flagella, pili, fimbriae, and nanowires. [11] [8] Some archaea possess very complex appendages known as hami. [12]
The pair attached to the first segment of the head are called primary antennae or antennules. This pair is generally uniramous, but is biramous in crabs and lobsters and remipedes. The pair attached to the second segment are called secondary antennae or simply antennae.
Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes , and is the place where almost all DNA replication and RNA synthesis ( transcription ) occur.
They possess an exoskeleton with a cuticle made of chitin, often mineralised with calcium carbonate, a body with differentiated segments, and paired jointed appendages. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. They form an extremely diverse group of up ...
The foundation of the cilium is the basal body, a term applied to the mother centriole when it is associated with a cilium. Mammalian basal bodies consist of a barrel of nine triplet microtubules, subdistal appendages and nine strut-like structures, known as distal appendages, which attach the basal body to the membrane at the base of the cilium.
The head is covered by hair-like or lamellar scales and found either as tufts on the frons or vertex (referred to as rough-scaled) or pressed close to the head (referred to as smooth-scaled). The sensory organs and structures on the head show great variety, and the shape and form of these structures, as also their presence or absence, are ...
The sensors are primarily single cells that detect light, chemicals, pressure waves and contact, and are present on the head, appendages (if any) and other parts of the body. [8] Nuchal ("on the neck") organs are paired, ciliated structures found only in polychaetes, and are thought to be chemosensors. [23]