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A lobster is heavily cephalized, with eyes, antennae, multiple mouthparts, and the brain (inside the armoured exoskeleton), all concentrated at the animal's head end. Cephalization is an evolutionary trend in animals that, over a sufficient number of generations, concentrates the special sense organs and nerve ganglia towards the front of the ...
A proboscis (/ p r oʊ ˈ b ɒ s ɪ s,-k ɪ s /) is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elongated nose or snout.
Placozoans have only three anatomical parts as tissue layers inside its body: the upper, intermediate (middle) and lower epithelia. There are at least six different cell types. [ 32 ] The upper epithelium is the thinnest portion and essentially comprises flat cells with their cell body hanging underneath the surface, and each cell having a ...
Two sets of muscles move the mandibles in the coronal plane of the mouth: abductor muscles move insects' mandibles apart ; adductor muscles bring them together . They do this mainly in opening and closing their jaws in feeding, but also in using the mandibles as tools, or possibly in fighting.
The insect body is divided into three parts: the head, thorax, and abdomen. [2] The head is specialized for sensory input and food intake; the thorax, which is the anchor point for the legs and wings (if present), is specialized for locomotion; and the abdomen is for digestion, respiration, excretion, and reproduction.
The head typically consists of two antennae, two compound eyes, two palpi, and a proboscis. [11] Lepidoptera have ocelli which may or may not be visible. They also have sensory structures called chaetosemata, the functions of which are largely unknown. The head is filled largely by the brain, the sucking pump, and its associated muscle bundles ...
All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion. [1] [2] The beak may also be referred to as the mandibles or jaws. [3]
[c] With an elongated body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the basis of the head. Opposed circular and longitudinal muscles enable peristaltic motion. Having a front end means that this part of the body encounters stimuli, such as food, favouring cephalisation, the development of a head ...