Melosira moniliformis

General Close


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

Shape Pill-shaped, almost spherical
Size Length 11 - 30 μm, diameter 17 - 70 μm
Colour Yellow-brown
Connection Mucous pads
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, Close



; along cell wall
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.

. Sexual/asexual. Close


In diatoms, the special cells that restore normal size following cell division. Auxospores are associated with sexual reproduction (Horner 2002).



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 Close


Describing the part of an ocean, river, or lake that is close to the shore. This can also refer to the organisms that live there. The littoral zone includes everything from the high water mark to near-shore areas that are permanently underwater. There is no fixed distance from shore or water depth that defines the end of the littoral zone. See also Neritic, which is directly below littoral.

, sometimes found in Close


Organisms that drift at the mercy of the currents.

Geographic Close


Widely distributed; occurring in many parts in the world.

Seasonal Very abundant in summer on Oregon coast
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).

23 - 36
Temperature -1 - 25 °C


Melosira borreri var. moniliformis (O. F. Müller) Grunow 1878 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).

Lysigonium moniliforme (O. F. Müller) Trevisan 1848 (homotypic)
Lysigonium moniliforme (O.F. Müller) Link 1820 (homotypic)
Conferva moniliformis O.F. Müller 1783 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).

, homotypic)
(Guiry and Guiry 2012)


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Coscinodiscophyceae
Subclass Coscinodiscophycidae
Order Melosirales
Family Melosiraceae
Genus Melosira
Species M. moniliformis (O. F. Müller) C. Agardh 1824

(Guiry and Guiry 2012)


Photosynthetic. Reproduces sexually and asexually. Auxospores present (Cupp 1943).


Cells are pill-shaped, from roughly cylindrical to almost spherical, and are usually connected in straight chains by mucous pads (Horner 2002). Close


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

have thick walls, and the valve face is flat with small, poorly developed Close


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

(difficult to see in Close


(light microscopy) "Using a microscope in which a beam of light passes through optical lenses to view an image of the specimen" (MCM LTER 2010).

). Close

Intercalary bands

Girdle bands that are furthest away from the valve (Smithsonian 2011).

Intercalary bands
are usually absent between valves, but are often seen connecting the Close


The outline or border that defines the shape of an organism or cell.

of dividing cells. Chloroplasts are numerous and discoid, located along the cell wall; the Close


(plural: nuclei) In eukaryotic cells, a membrane-bound organelle that contains the cell's genetic information; the nucleus controls the activities of the cell by controlling gene expression.

is central (Cupp 1943). Cells are yellow-brown in colour.

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
are present throughout the whole valve surface, but are more numerous on the valve face and the margins (Horner 2002). "In valve view Close


(plural: puncta) A sharp tip or small point on any part of an organism's anatomy.

in partly radiating, mostly irregular short lines; on valve Close


In diatoms, "the part of a valve that extends from the valve face, forming the valve edge." It is visible when the frustule is viewed in girdle view (Spaulding 2010).

and 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).

in more regular crossrows" (Cupp 1943).


Diameter: 17 - 70 μm
Length: 11 - 30 μm
Puncta on valve: 22 - 24 in 10 μm
Puncta on girdle: 15 in 10 μm
(Cupp 1943, Horner 2002)

Similar species

Stephanopyxis spp., which have hexagonal Close


Often used to describe holes (areolae) on the valve surface of diatom frustules.

on the cell surface and very distinct spines connecting adjacent cells.

Harmful effects

None known.


Littoral, but occasionally found in plankton (Cupp 1943).


Geographic: Cosmopolitan (Horner 2002), but sometimes considered a cold-water species (Cupp 1943).
Seasonal: Can be very abundant in the summer on the Oregon coast (McIntire and Overton 1971). More often seen from late winter to early spring in Northern European seas (Kraberg et al. 2010).
Local: Information not available.

Growth conditions

Growth may be inhibited by high light intensities when daylength is long (Castenholz 1964).

Environmental Ranges

Depth range (m): 0 - 160
Temperature range (°C): -0.863 - 24.625
Nitrate (μmol L-1): 0.793 - 12.253
Salinity: 22.974 - 35.625
Oxygen (mL L-1): 4.855 - 8.817
Phosphate (μmol L-1): 0.071 - 1.500

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): 1.309 - 37.729
(OBIS 2012, cited in EOL 2012)

Bloom characteristics

Information not available.


Castenholz, R. W. 1964. The effect of daylength and light intensity on the growth of littoral marine diatoms in culture. Physiologia Plantarum. 17(4): 951-963.

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. Melosira moniliformis. Accessed 29 Jan 2012.

Guiry, M. D. and Guiry, G. M. 2012. Melosira moniliformis (O. F. Müller) C. Agardh. Accessed 29 Jan 2012.

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.

McIntire, D. and Overton, W. S. 1971. Distributional Patterns in Assemblages of Attached Diatoms from Yaquina Estuary, Oregon. Ecology. 52(5): 758-777.

Ocean Biogeographic Information System (OBIS). 2012. Melosira moniliformis. Accessed 29 Jan 2012.

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