Search results
Results from the WOW.Com Content Network
The earliest known fleas lived in the Middle Jurassic; modern-looking forms appeared in the Cenozoic. Fleas probably originated on mammals first and expanded their reach to birds. Each species of flea specializes, more or less, on one species of host: many species of flea never breed on any other host; some are less selective.
The human flea (Pulex irritans) – once also called the house flea [1] – is a cosmopolitan flea species that has, in spite of the common name, a wide host spectrum. It is one of six species in the genus Pulex ; the other five are all confined to the Nearctic and Neotropical realms . [ 2 ]
Echidnophaga gallinacea, also known as the hen flea or sticktight flea, is part of the 2,500 known flea types in the Siphonaptera order. Echidnophaga gallinacea appear dark brown in colour and is a small flea measuring approximately 2 millimetres in length, which is half the size of the common cat flea. [1]
Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye [1]. A blind spot, scotoma, is an obscuration of the visual field.A particular blind spot known as the physiological blind spot, "blind point", or punctum caecum in medical literature, is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the ...
The dark blue, teal, and gold tapetum lucidum from the eye of a cow Retina of a mongrel dog with strong tapetal reflex. The tapetum lucidum (Latin for 'bright tapestry, coverlet'; / t ə ˈ p iː t əm ˈ l uː s ɪ d əm / tə-PEE-təm LOO-sih-dəm; pl.: tapeta lucida) [1] is a layer of tissue in the eye of many vertebrates and some other animals.
Schematic representation of a Euglena cell with red eyespot (9) Schematic representation of a Chlamydomonas cell with chloroplast eyespot (4). The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids.
The bioluminescence can be produced from compounds during the digestion of prey, from specialized mitochondrial cells in the organism called photocytes ("light producing" cells), or, similarly, associated with symbiotic bacteria in the organism that are cultured. [citation needed]
Listed here are fleas commonly encountered by humans that could potentially be used for DNA identification. Sticktight and chigoe flea, Family Hectopsyllidae (formerly Tungidae) Cat flea (Ctenocephalides felis) Northern rat flea (Nosopsyllus fasciatus) Human flea (Pulex irritans) Oriental rat flea (Xenopsylla cheopis)