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Asteromphalus heptactis

Classification
General Close

Centric

(diatoms) Having radial symmetry, i.e., cell is shaped like a coin or a tuna can or a soup can.

Centric diatom
Description
Shape Close

Discoid

Disc-shaped.

Discoid
Size Length 38 - 175 μm
Colour Yellow-brown
Connection None
Covering Silica Close

Frustule

In diatoms, the hard and porous silica cell wall (Horner 2002).

frustule
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Flagellum

(plural: flagella) A tail-like projection that sticks out from the cell body and enables movement.

Flagella		 None
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Chloroplast

An organelle in the cell that contains the cell pigments (Horner 2002). This is where photosynthesis occurs. A chloroplast is a specialized chromatophore.

Chloroplast		 Numerous and arranged Close

Radial

(symmetry) Describing a shape that many axes of symmetry. That is, it does not have a left and right like humans do (bilateral symmetry), but can be divided into equal halves no matter where you place the axis. Some examples of radially symmetrical organisms include sea stars and centric diatoms like Thalassiosira.

radially
Behaviour
Lifestyle Close

Photosynthesis

The chemical process by which light energy, water and carbon dioxide are combined to produce oxygen and organic compounds. Photoautotrophic organisms (plants and algae) use this reaction to produce their own food.

Photosynthetic
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Bloom

A rapid increase or accumulation of algal populations in an aquatic system. This will likely involve one or a few dominant phytoplankton species. This follows seasonal patterns (i.e., spring, summer or fall bloom) with dominant species being those that are best adapted to the environmental conditions of that time period. Discolouration of the water may be observed because of the algae's pigmentation. Blooms are often green but may be yellow-brown or red depending on the species present.

Bloom		 Information not available
Harmful effects None known
Distribution
Habitat Oceanic
Geographic Temperate
Seasonal Blooms in early spring in the Gulf of California
Growth Conditions
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Salinity

The dissolved ion content of a body of water. Can be measured in the following units: parts per thousand (PPT or ‰), practical salinity units (PSU), and absolute salinity (g/kg). PPT is measured by weight, denoting the number of parts salt per thousand total parts or a value of 10-3. PSU measures the conductivity of saltwater and compares it in a ratio to a standard KCl solution (because this is a ratio, salinity measured in this way can also be written without units). The newest unit of salinity is absolute salinity, which uses the mass fraction of salt in seawater (g salt per kg seawater) rather than its conductivity (TEOS-20 2010).

Salinity		 30 - 36
Temperature -1 - 29 °C

Synonym(s)

Asterolampra areolata A. Mann 1925 Close

Heterotypic

A difference in type. In naming species, a heterotypic synonym is one that comes into being when a taxon becomes part of a different taxon. Compare to homotypic.

(heterotypic)
Asterolampra ralfsiana (G. Norman) Grunow 1876 (heterotypic)
Asteromphalus reticulatus Cleve 1873 (heterotypic)
Asterolampra heptactis (Brébisson) Greville 1860 (heterotypic)
Spatangidium ralfsianum G. Norman 1859 (heterotypic)
Spatangidium heptactis Brébisson 1857 Close

Basionym

The original name for an organism. In botany, the original published nomenclature from which a new binomial nomenclature is derived for a particular group of organisms (Tindall 1999).

(basionym, Close

Homotypic

Expressing the same fundamental type or structure; may or may not be symmetrical (e.g., the two valves of a diatom, where they are the same shape and appearance, but one is bigger than the other). In naming species, a homotypic synonym is one that comes into being when a taxon gets a new name (without being added to an already existing taxon).

homotypic)
(Guiry and Guiry 2012)

Classification

Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Coscinodiscophyceae
Subclass Coscinodiscophycidae
Order Asterolamprales
Family Asterolampraceae
Genus Asteromphalus
Species A. heptactis (Brébisson) Ralfs 1861

(Guiry and Guiry 2012)

Lifestyle

Photosynthetic. Reproduces sexually and asexually.

Description

Cells are discoid and solitary. Close

Valve

In diatoms, the structurally distinct halves of the cell wall (Becker 1996).

Valve surface consists of seven rays of unequal lengths extending from a roughly central region, with one ray much narrower than the rest, making the valve face resemble a sand dollar (pers. obs.). The rays and central region are smooth, while the rest of the valve is Close

Areolated

Synonym: perforated. Describing a surface that has many holes. Often used to describe the valve surface of diatom frustules.

areolated. Rays are raised above the rest of the valve, making the valve surface radially undulate (visible in Close

Girdle

In diatoms, the portion of the cell wall between the two valves of a cell; made up of intercalary bands (bands closest to the valves) and connecting bands (bands in the middle of the girdle). In dinoflagellates, the equivalent of a cingulum or transverse furrow (Horner 2002).

girdle view; Cupp 1943). Separating lines in the central area are bent or branched (Hasle and Syvertsen 1997). Chloroplasts are numerous and often arranged radially (Cupp 1943). Cells are yellow-brown in colour.
Wider rays have a "large opening at the outer end with the external opening of a Close

Labiate process

In diatoms, a simple slit in the valve wall with two internal lips, one on each side of the slit. They can be useful in identification because they are positioned differently in different species (Horner 2002).

labiate processes below," and the narrow ray has a labiate process that "terminates inside the ray tube" (Horner 2002).

Measurements

Diameter: 38 - 175 μm
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Areola(e)

In diatoms, the regularly repeated hexagonal holes on the valve walls (HPP 2003).

Areolae: 5 - 7 in 10 μm
Size of central region: ¼ - ⅓ of diameter
(Cupp 1943, Hasle and Syvertsen 1997)

Similar species

None.

Harmful effects

None known.

Habitat

Oceanic (Cupp 1943).

Distribution

Geographic: Temperate species (Cupp 1943).
Seasonal: Sometimes forms blooms in early spring in the Gulf of California (Round 1967), in mid-winter in the Northeastern Pacific (Takahashi et al. 1990) and in early fall near the eastern coast of Adriatic Sea (Bakran-Petricioli et al. 1998).
Local: "Occasionally found in large numbers off California but usually not numerous. Reported from Scotch Cap, Alaska and from Gulf of California" (Cupp 1943).

Growth conditions

Information not available.

Environmental Ranges

Depth range (m): 0 - 300
Temperature range (°C): -1.462 - 29.468
Nitrate (μmol L-1): 0.056 - 34.037
Salinity: 30.119 - 36.252
Oxygen (mL L-1): 4.139 - 8.095
Phosphate (μmol L-1): 0.046 - 2.358
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Silicic acid

A general term to describe chemical compounds containing silicon, oxygen and hydrogen with a general formula of [SiOx(OH)4-2x]n. Diatoms polymerize silicic acid into biogenic silica to form their frustules (Azam and Chisholm 1976).

Silicate (μmol L-1): 0.769 - 92.735
(OBIS 2012, cited in EOL 2012)

Bloom characteristics

Information not available.

References

Bakran-Petricioli, T., Petricioli, D. and Viličić, D. 1998. Taxonomic composition and seasonal distribution of microphytoplankton in the Krka River estuary. Natura Croatica. 7(4): 307-319.

Cupp, E. E. 1943. Marine Plankton Diatoms of the West Coast of North America. University of California Press. Berkeley, California. 238.

Encyclopedia of Life (EOL). 2012. Asteromphalus heptactis. http://eol.org/pages/912759/overview. Accessed 07 Jan 2012.

Guiry, M. D. and Guiry, G. M. 2012. Asteromphalus heptactis (Brébisson) Ralfs. http://www.algaebase.org/search/species/detail/?species_id=37184. Accessed 07 Jan 2012.

Hasle, G. R. and Syvertsen, E. E. 1997. Marine diatoms. In: Tomas, C. R. (ed.) Identifying Marine Phytoplankton. Academic Press, Inc., San Diego. 5-385.

Horner, R. A. 2002. A Taxonomic Guide To Some Common Phytoplankton. Biopress Limited, Dorset Press, Dorchester, UK. 200.

Ocean Biogeographic Information System (OBIS). 2012. Asteromphalus heptactis. http://www.iobis.org/mapper/?taxon_id=407176. Accessed 07 Jan 2012.

Round, F. E. 1967. The phytoplankton of the Gulf of California. Part I. Its composition, distribution and contribution to the sediments. Journal of Experimental Marine Biology and Ecology. 1(1): 76-97.

Takahashi, K., Billings, J. D. and Morgan, J. K. 1990. Oceanic Province: Assessment from the Time-Series Diatom Fluxes in the Northeastern Pacific. Limnology and Oceanography. 35(1): 154-165.