Oxyphysis oxytoxoides

General Dinoflagellate
Shape Elongated spinning top
Size Length 60 - 68 μm, width 16 - 24 μm
Colour Depends on diet
Connection None (solitary)
Covering Cellulose Close


(plural: thecae) Cell wall. In dinoflagellates, it is composed of cellulose plates within vesicles (Horner 2002).



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

Two unequal


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

Lifestyle Close


An organism that cannot convert inorganic carbon into a usable energy source. Instead, it consumes other organisms to obtain organic carbon for growth.

. Asexual Close

Binary fission

A form of asexual reproduction where one cell divides into two identical cells. All prokaryotes and some eukaryotes reproduce in this manner. Compare with mitosis, where the nucleus must also divide, adding an extra step to the process.

(binary fission


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.

No information available
Harmful effects None known
Habitat Coastal and open ocean
Geographic Temperate to subtropical
Seasonal Mid-summer
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).

34 - 35
Temperature 20 - 23 °C




Empire Eukaryota
Kingdom Protozoa
Subkingdom Biciliata
Infrakingdom Alveolata
Phylum Dinoflagellata
Class Dinophyceae
Order Dinophysiales
Family Dinophysiaceae
Genus Oxyphysis
Species O. oxytoxoides Kafoid 1926

(Guiry and Guiry 2011)


O. oxytoxoides is a heterotrophic dinoflagellate that feeds on ciliates and other Close


A diverse group of eukaryotic microorganisms which range from "animal-like" protozoa to "plant-like" algae. This is an older, informal term referring to many simple organisms that do not fit well into the kingdoms of plants, animals or fungi. This means that diatoms, dinoflagellates, amoebae, ciliates, slime moulds, and many other groups of organisms can be called protists.

using feeding tube (EOL 2011). It reproduces asexually by binary fission (EOL 2011).


They are Close


Describes a tube shape that widens at both ends and tapers in the middle.

and laterally compressed. Cells are always longer than they are wide: they are 60 - 68 μm long and 16 - 24 μm wide. The cell's Close


(dinoflagellates) "In dinokont dinoflagellates, a furrow encircling the cell one or many times" (Horner 2002). It is also known as the girdle or transverse groove and may be located at, above, or below the midpoint of the cell with the left and right ends meeting or displaced form one another (Horner 2002). In diatoms, this term describes the collective elements of a diatom girdle: "The cingulum is made up of delicate silica bands that join the two valves of a frustule. Most diatoms possess a cingulum, although some may not" (Spaulding et al. 2010).

is about ⅓ cell length from the apex. The Close


In thecate dinoflagellates, the anterior part of a dinokont cell above the cingulum. The equivalent of epicone for naked dinoflagellates.

is narrower than the Close


In thecate dinoflagellates, the posterior part of a dinokont cell above the cingulum. The equivalent of a hypocone for naked dinoflagellates.

(Smithsonian 2011) being slightly asymmetrical, ending in a straight Close


The apical or antapical extensions found in some armoured dinoflagellates; they contain cytoplasm, are covered in thecal plates and can be hollow or partially solid (Horner 2002).

(Horner, 2002). The hypotheca has Close


Relating to a side-to-side direction.

compressed sides with a blunt point at the tip. The cell has a very short Close


"In dinokont dinoflagellates, the longitudinal area on the ventral surface that forms a furrow or depression and houses the longitudinal (trailing) flagellum" (Horner 2002).

with narrow Close

Sulcal list

(left and right) In dinokont dinoflagellates, a well-defined groove on the ventral surface that is supported by ribs.

sulcal lists
. O. oxytoxoides is heterotrophic and hence does not have any chloroplasts, so its colour depends on the colour of its food (Horner 2002). It looks like a spindle or an elongated spinning top.


Length: 60 - 68 μm
Width: 16 - 24 μm
(Smithsonian 2011)

Similar species

Oxytoxum diploconus (Horner 2002). The hypotheca in O. diploconus is cone-shaped while the hypotheca in Oxyphysis has rounder sides.

Harmful effects

None known.


Coastal and open ocean, in temperate to subtropical waters (Horner 2002).


Oxyphysis oxytoxoides was earlier thought to live only in the cold coastal waters of the Pacific Ocean (Smithsonian 2011). It is now known to occur throughout the cold temperate to subtropical water of the Atlantic Ocean and the Mediterranean Sea as well (EOL 2011). Oxyphysis oxytoxoides has sometimes been seen in the Indian River lagoon and it is speculated that it might have entered the lagoon via inlets from cool nearshore waters (Smithsonian 2011).

Environmental Ranges

Depth range (m): 0 - 15
Temperature range (°C): 19.811 - 23.653
Nitrate (μmol L-1): 0.349 - 8.097
Salinity: 34.513 - 35.114
Oxygen (mL L-1): 4.863 - 5.068
Phosphate (μmol L-1): 0.077 - 1.151

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): 2.873 - 6.865

Bloom characteristics

No information available.


Encyclopedia of Life (EOL). Oxyphysis oxytoxoides Kofoid 1926. http://www.eol.org. Accessed 18 Sept 2011.

Guiry, M. D. and Guiry, G. M. 2011 Oxyphysis oxytoxoides Kofoid 1926. http://www.algaebase.org/search/species/detail/?species_id=45678. Accessed 24 Sept 2011.

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

Smithsonian Institution. 2011. Oxyphysis oxytoxoides Kafoid 1926. http://www.sms.si.edu/irlspec/Oxyphy_oxytox.htm. Accessed 16 Oct 2011.

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