Asteromphalus heptactis

General Close


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

Shape Close



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


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



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



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

Numerous and arranged Close


(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.

Lifestyle Close


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.



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.

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


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).

30 - 36
Temperature -1 - 29 °C


Asterolampra areolata A. Mann 1925 Close


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.

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


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).

, Close


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).

(Guiry and Guiry 2012)


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)


Photosynthetic. Reproduces sexually and asexually.


Cells are discoid and solitary. Close


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

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


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

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


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).

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).


Diameter: 38 - 175 μm


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

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

Similar species


Harmful effects

None known.


Oceanic (Cupp 1943).


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

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).

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

Bloom characteristics

Information not available.


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. Accessed 07 Jan 2012.

Guiry, M. D. and Guiry, G. M. 2012. Asteromphalus heptactis (Brébisson) Ralfs. 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. 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.

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