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Chaetoceros similis

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 Elliptic cylinder
Size Large diameter 7 - 17 μm
Colour Yellow-brown
Connection Crossing of adjacent Close

Spine

In some diatoms, "closed or solid structures projecting from the cell wall;" in dinoflagellates, solid projections that usually taper to a point.

spines
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		 Two
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. Sexual/asexual. Close

Resting spore

In diatoms, a cell that requires a dormancy period prior to germination and can survive for several years; usually developed to survive adverse conditions. They are commonly observed in centric but not pennate diatoms. The morphology of the spore may be similar or different from a vegetative cell; they usually have heavily silicified walls and are rich in storage products (Horner 2002).

Resting spores present
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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 Close

Neritic

Describing shallow, near-shore areas and the organisms that live there. Refers to shallow marine waters ranging from the low tide mark to the continental shelf. Varying amounts of sunlight penetrate the water, allowing photosynthesis by both phytoplankton and bottom-dwelling organisms. Close proximity to land favours high nutrient content and biological activity (Encyclopedia Britannica 2011).

Neritic
Geographic Temperate to cold waters
Seasonal Late spring to early summer
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		 18 - 36
Temperature -1 - 25 °C

Synonym(s)

None.
*Sometimes referred to as C. simile (Guiry 2012).

Classification

Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Bacillariophyceae
Subclass Coscinodiscophycidae
Order Chaetocerotales
Family Chaetocerotaceae
Genus Chaetoceros
Species C. similis Cleve 1896

(Guiry and Guiry 2012)

Lifestyle

Photosynthetic. Reproduces sexually and asexually (Guiry 2012). Resting spores present (Cupp 1943).

Description

Cells are connected in short, straight chains. Close

Valve

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

Valves have a raised centre where adjacent cells touch, which, together with the spines, form a distinct figure-eight-shaped Close

Aperture

"In some diatoms, the space between the valves of adjacent cells in chains" (Horner 2002).

aperture. Spines are very straight and arise from the corners of the cell, crossing just outside the cells then extending out diagonally. Terminal spines are similar but may be slightly thicker. A small but distinct groove is present between the valves and the 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 zone. Cells each have two chloroplasts (Cupp 1943). Cells are yellow-brown in colour.
Resting spores are globular and located centrally, with valves that are covered with tiny Close

Spicules

Small, needlelike structures.

spicules (Cupp 1943).

Measurements

Large diameter Close

Apical

(axis, spine) The region of the apex or point. Refers to the most anterior point or region of the cell (HPP 2003).

(apical axis): 7 - 17 μm
(Hasle and Syvertsen 1997)

Similar species

None.

Harmful effects

None known.

Habitat

Neritic (Cupp 1943).

Distribution

Geographic:
Temperate to cold waters (Hasle and Syvertsen 1997).
Seasonal:
(See Local).
Local:
Found from late spring to early summer in Saanich Inlet, BC (McQuoid and Hobson 1995). Present off California, but never in large numbers (Cupp 1943).

Growth conditions

May be favoured by temperatures between 12 - 15 °C and Close

Photoperiod

The amount of time in a day that an organism is exposed to daylight. This varies between seasons, with photoperiods being longer in the summer and shorter in the winter.

photoperiods around 16 h (McQuoid and Hobson 1995).

Environmental Ranges

Depth range (m): 0 - 200
Temperature range (°C): -1.383 - 24.625
Nitrate (μmol L-1): 0.567 - 14.229
Salinity: 17.940 - 35.659
Oxygen (mL L-1): 4.855 - 8.936
Phosphate (μmol L-1): 0.152 - 1.370
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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): 1.309 - 35.210
(OBIS 2012, cited in EOL 2012)

Bloom characteristics

Information not available.

References

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. Chaetoceros similis. http://eol.org/pages/2540183/overview. Accessed 31 Mar 2012.

Guiry, M. D. 2012. Chaetoceros similis Cleve, 1896. http://www.marinespecies.org/aphia.php?p=taxdetails&id=149127. Accessed 31 Mar 2012.

Guiry, M. D. and Guiry, G. M. 2012. Chaetoceros similis Cleve. http://www.algaebase.org/search/species/detail/?species_id=37462. Accessed 31 Mar 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.

Kraberg, A., Baumann, M. and Durselen, C. D. 2010. Coastal Phytoplankton: Photo Guide for Northern European Seas. Verlag Dr. Friedrich Pfeil, Munchen, Germany. 204.

Ocean Biogeographic Information System (OBIS). 2012. Chaetoceros similis. http://www.iobis.org/mapper/?taxon_id=419713. Accessed 31 Mar 2012.