HALIOTIS ASININA PDF

Habitat[ edit ] This abalone dwells in shallow water coral reef areas of the intertidal and sublittoral zones, commonly reaching a depth around 10 m. They graze amongst turf algae and inhabit the undersides of boulders and coral bommies. The species has a pelagobenthic life cycle that includes a minimal period of three to four days in the plankton. Biomineralisation begins shortly after hatching, with the fabrication of the larval shell protoconch over about a hour period. The initial differentiation of biomineralising cells is likely to include a localised thickening of the dorsal ectoderm followed by an invagination of cells to form the shell gland.

Author:Negore Yotaxe
Country:Latvia
Language:English (Spanish)
Genre:Video
Published (Last):7 April 2011
Pages:87
PDF File Size:19.7 Mb
ePub File Size:10.80 Mb
ISBN:796-7-77598-416-4
Downloads:52028
Price:Free* [*Free Regsitration Required]
Uploader:Dotilar



Habitat Edit This abalone dwells in shallow water coral reef areas of the intertidal and sublittoral zones, commonly reaching a depth around 10 m. They graze amongst turf algae and inhabit the undersides of boulders and coral bommies.

The species has a pelagobenthic life cycle that includes a minimal period of three to four days in the plankton. Biomineralisation begins shortly after hatching, with the fabrication of the larval shell protoconch over about a hour period. The initial differentiation of biomineralising cells is likely to include a localised thickening of the dorsal ectoderm followed by an invagination of cells to form the shell gland. The shell gland then evaginates to form the shell field which expands through mitotic divisions to direct the precipitation of calcium carbonate CaCO3 via the secretion of organic molecules.

In this way the larval shell protoconch is formed. The construction of the haliotid protoconch is complete following torsion. These structures allow the veliger larva to completely retract into a protective environment and rapidly fall out of the water column. The protoconch remains developmentally inert until the animal contacts a specific cue that initiates the process of metamorphosis. The early postlarval shell is more robust and opaque than the larval shell but has no pigmentation.

While the initial teloconch is not pigmented, it is textured and opaque such that postlarval shell growth is easily discerned from the larval shell. The white arrow indicates the metamorphosis from the larval shell protoconch to juvenile shell. A photograph of two postlarvae on a coralline algal surface.

The juvenile Haliotis asinina teloconch rapidly develops a uniform maroon colouration several weeks after metamorphosis, similar to the crustose coralline algae CCA that the larva has settled upon. Structurally, a pronounced series of ridges and valleys and a line of respiratory pores tremata have appeared.

Furthermore, it is at this stage of development that the first recognisable tablets of nacre can be detected. Colourmetrically, the uniform maroon background is now interrupted by oscillations of a pale cream colour, and is punctuated by a pattern of dots that only occur on ridges which are blue when overlying a maroon field and orange when overlying a cream field.

This pattern is gradually lost with growth, as the shell becomes thicker and more elongate. Blue and orange dots however persist on the ridges.

These large scale morphological changes are accompanied by mineralogical and crystallographic changes. In larger shells, a ventral cap of CaCO3 that underlies the tablets of aragonitic nacre continues to thicken. Note the similarity of the markings to the Sierpinski triangle. The growth rate of Haliotis asinina is the fastest of all the abalones.

GUISANTES VACANCES PDF

traduire de

Description[ edit ] The iridescent inside surface of a red abalone shell from Northern California : The coin is about one inch in diameter. The thick inner layer of the shell is composed of nacre , which in many species of abalone is highly iridescent, giving rise to a range of strong, changeable colors, which make the shells attractive to humans as decorative objects, in jewelry, and as a source of colorful mother-of-pearl. The shell of abalones is convex , rounded to oval shape, and may be highly arched or very flattened. The shell of the majority of species is ear-shaped, presenting a small, flat spire and two to three whorls.

MANIFIESTOS EN NAHUATL DE EMILIANO ZAPATA PDF

haliotis asinina

Habitat Edit This abalone dwells in shallow water coral reef areas of the intertidal and sublittoral zones, commonly reaching a depth around 10 m. They graze amongst turf algae and inhabit the undersides of boulders and coral bommies. The species has a pelagobenthic life cycle that includes a minimal period of three to four days in the plankton. Biomineralisation begins shortly after hatching, with the fabrication of the larval shell protoconch over about a hour period.

DOA ROSARIO PEMBEBASAN PDF

.

Related Articles