Dictyochophyceae

Pteridomonas (ter-rid-owe-moan-ass) a colourless pedinellid (stramenopile) flagellate. Like other pedinellids, it has a single apical flagellum surrounded by a wreath of fine arms, and usually attached to the substrate by a fine stalk. The stalk is contractile and may also release from the substrate. The flagellum beats with an undulating beat pattern. Phase contrast.

Portrait of Pteridomonas, a small silicoflagellate with a long thin stalk. Tentacles surround the single apical flagellum. Posterior contractile vacuole can be seen here. Very similar to Actinomonas, which has posterior tentacles as well. The two species also have ultrastructural differences. From freshwater pond near Boise, Idaho. Oblique illumination

Portrait of Pteridomonas, a small silicoflagellate with a long thin stalk. Tentacles surround the single apical flagellum. Very similar to Actinomonas, which has posterior tentacles as well. From freshwater pond near Boise, Idaho.

Pteridomonas pulex Penard Cells spherical, usually broader than the length, in optical profiles heart to kindney-shaped, 6-12 microns long. Stalk is long and thin. Nucleus is in central. Flagellum is 3-4 times the cell length. 12-18 pseudopodia arise at the base of the flagellum and surround the anterior end of the cell.

Pteridomonas danica Patterson and Fenchel, 1985. A colourless pedinellid, body 4.5-5 microns long, with one apical flagellum emerging from a slight depression at the anterior of the cell. The flagellum is surrounded by 12 stiffarms. Posterioly, the body gives rise to a stalk. The stalk and arms may be withdrawn in swimming cells.

Phase contrast image of a small group of these heterotrophic flagelates. A single apical flagellum draws water twoards the thin arms that intercept food particles.

Ciliophrys (silly-off-rees), a pedinellid stramenopile, with a single flagellum. The cell may exist as a non-swimming form with radiating arms, and with the flagellum inactive or beating in a languid figure of 8 motion. The arms can be resorbed, and the cell can then swim with the flagellum pulling the cell forward. This is the heliozoon form, with a nucleus in the centre of the cell. Phase contrast.

Ciliophrys (silly-off-rees), a pedinellid stramenopile, with a single flagellum. The cell may exist as a non-swimming form with radiating arms, and with the flagellum inactive or beating in a languid figure of 8 motion. The arms can be resorbed, and the cell can then swim with the flagellum pulling the cell forward. This is the heliozoon form, with a nucleus in the centre of the cell. Phase contrast.

Ciliophrys (silly-off-rees), a pedinellid stramenopile, with a single flagellum. The cell may exist as a non-swimming form with radiating arms, and with the flagellum inactive or beating in a languid figure of 8 motion. The arms can be resorbed, and the cell can then swim with the flagellum pulling the cell forward. This is the heliozoon form, with a nucleus in the centre of the cell. Phase contrast.

Ciliophrys (silly-off-riss) infusionum Cienkowski, 1876. Helioflagellate, in the heliozoan stage the cells are about 4 - 9 microns across, and have a central nucleus and one flagellum held in a figure of eight. The cells are spherical with delicate pseudopodia extending radially from the body and bearing extrusomes. The cells may change from the heliozoan stage with pseudopodia and a slow beating flagellum to a swimming flagellate without pseudopodia and with the flagellum beating rapidly. In swimming cells, the nucleus is located apically. Observed to consume suspended bacteria. When feeding, bacteria adhere to the pseudopodia and then are drawn to the body. The cells eat diatoms up to 18 microns long. Sometimes common.

Ciliophrys infusionum Cienkowski, 1876. Ciliophrys, in the heliozoan stage the cells are about 4 - 9 microns across, and have a central nucleus and one flagellum held in a figure of eight. The cells are spherical with delicate pseudopodia extending radially from the body and bearing extrusomes. The cells may change from the heliozoan stage with pseudopodia and a slow beating flagellum to a swimming flagellate without pseudopodia and with the flagellum beating rapidly. In swimming cells, the nucleus is located apically. Observed to consume suspended bacteria. When feeding, bacteria adhere to the pseudopodia and then are drawn to the body. The cells eat diatoms up to 18 microns long.

Portrait of Ciliophrys infusionum (Cienkowski,1876), one of the colourless pedinellid flagellates (also referred to as a helioflagellate). When at rest on the substrate tentacles(axopodia supported by one triplet of microtubules) of with fine granules are distributed over the entire surface and the single flagellum is held in a tight S configuration hardly moving. When swimming, tentacles withdraw and the cell surface appears smooth, the flagellum beating more rapidly in sine wave fashion. From standing freshwater near Boise, Idaho. Phase contrast.

Portrait of Ciliophrys infusionum (Cienkowski,1876), one of the colourless pedinellid flagellates (also referred to as a helioflagellates). When at rest on the substrate, tentacles (axopodia supported by one triplet of microtubules) with fine granules are distributed over the entire cell surface and the single flagellum is held in a tight S configuration hardly moving. When swimming, tentacles withdraw and the cell surface appears smooth, the flagellum beating more rapidly in sine wave fashion. From a commercial marine aquarium in Boise, Idaho. DIC.

Portrait of Ciliophrys infusionum (Cienkowski,1876), one of the colourless pedinellid flagellates (also referred to as a helioflagellates). When at rest on the substrate, tentacles (axopodia supported by one triplet of microtubules) with fine granules are distributed over the entire cell surface and the single flagellum is held in a tight S configuration hardly moving. When swimming, tentacles withdraw and the cell surface appears smooth, the flagellum beating more rapidly in sine wave fashion. From a commercial marine aquarium in Boise, Idaho. DIC.

Dictyocha (dick-tee-oke-a) is a silicoflagellate, a type of flagellate which is quite common in marine waters, although there are very few species. The cells contain an open polygonal skeleton of silica with radiating spines. The skeleton survives when the organism dies, and so is often seen on its own. This cell is distressed . Phase contrast image by Dave Caron.

This skeleton of the flagellate Dictyocha was prepared by bleaching and cleaning from a marine water column sample taken off Martha's Vineyard in Vineyard Sound, Massachusetts. Differential interference contrast optics, image by Charley O'Kelly.

Dictyocha fibula Ehrenberg, 1839. Silicoflagellate with siliceous skeleton (basal ring) with four sides, but without the apical ring. Spines project from the corners of the outer hexagon, internal projections form irregular connections. Bars also arise inwards and may fuse to form a central arch. The cytoplasm extends over the skeleton, fine pseudopodia usually project from the tops of the spines. Many small plastids, single emergent flagellum. Mostly 30-80microns Marine

Dictyocha fibula longispina Lemmermann, 1901. Silicoflagellate with siliceous skeleton (basal ring) with four sides, but without the apical ring. Spines project from the corners of the outer hexagon, internal projections form irregular connections. Bars also arise inwards and may fuse to form a central arch. The cytoplasm extends over the skeleton, fine pseudopodia usually project from the tops of the spines. Many small plastids, single emergent flagellum. Radial spines of the basal ring of equal length, approx. 12-15 microns long. Basal ring 23-27 microns Marine.

Dictyocha fibula messanensis (Haeckel) Lemmermann, 1901. The silica skeleton consists of a four-side basal ring (20-30 microns) with a tapered radial spine (15-22 microns) at each of the angles. On the sides of each strut forming the basal ring are small abapically directed protuberances. Four supporting bars project from the basal ring and join with a short bar. Marine.

Dictyocha fibula hexagona Marshall, 1934. Silicoflagellate with siliceous skeleton (basal ring) with six major sides like Distephanus, but without the apical ring. Spines project from the corners of the outer hexagon, internal projections form irregular connections. Bars also arise inwards and may fuse to form a central arch. The cytoplasm extends over the skeleton, fine pseudopodia usually project from the tops of the spines. Many small plastids, single emergent flagellum, reported from the Great Barrier Reef, maximum width 86 microns

A silicoflagellate & its skeleton: from a Lugol's-fixed sample taken in the NW Med in October.

Distephanus octangulatus Wailes, 1931. Silicieous skeleton consisting of a frame forming a truncated cone, the basal ring octagonal with an external projection at each angle, from the centers of four sides arise supporting bars attached to the angles of the square apical ring, the side openings provided with small semicircular projections at the centers of the longer sides. Diameter of basal ring 35 microns