Download género Volvox

género Volvox
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Description of volvox
Colonies large (up to 1.5 mm), more or less spherical to ellipsoidal, usually containing many hundreds to
thousands (up to 60,000) cells in a single layer on periphery of a common gelatinous matrix; colonial
boundary tripartite, each cell also surrounded by an individual extracellular matrix; 2 cell types, somatic
and reproductive; somatic cells identical, spherical, ellipsoidal, pyriform or stellate, with 2 outwardly
directed flagella; neighbouring cells attached by cytoplasmic connections; chloroplast single, cupshaped or irregularly disciform, with a single (rarely several) pyrenoid(s); eyespot single, usually largest
in anterior cells and progressively smaller or absent in posterior cells; nucleus more or less central;
contractile vacuoles 2-6; reproduction, both asexual and sexual, restricted to relatively few reproductive
cells (gonidia) which lose flagella and are somewhat larger than somatic cells; asexual reproduction by
formation of 2-80 daughter colonies; initial sequence of cell divisions leading to small hollow spheres of
cells or plakeas, in which flagellar bases and nuclei are oriented inwards; new gonidial cells being
formed by unequal division of certain cells early in cleavage process; developing daughter colonies
undergo inversion; sexual reproduction strictly oogamous; most species heterothallic, some
homothallic, either monoecious or dioecious, some species heteromorphic with dwarf male colonies;
female reproductive cells (2 to 700 per colony) enlarging to form oogonia with single non-flagellated
eggs (oospheres); male reproductive cells dividing and developing into plate-like or globose sperm
packets or plakeas of 16-512 biflagellate spindle-shaped antherozoids; zygotes thick-walled, smooth or
variously ornamented, often with reddish contents; on germination, a single (rarely 4) biflagellate
(sometimes aflagellate) gone cell escaping from zygote wall and dividing into a gone colony; nutrition
phototrophic or photo-organotrophic; common, in bogs, pools, ponds, ditches, but most species with
restricted geographical distribution.
Statistics of barcoding coverage 1
Barcode of Life Data Systems (BOLD) Stats
Specimen Records:38
Specimens with Sequences:37
Specimens with Barcodes:35
Species:16
Species With Barcodes:16
Public Records:37
Public Species:16
Public BINs:0
References
1. © Barcode of Life Data Systems, some rights reserved