Peranemidae

Urceolus sabulosus Stokes, 1886. Cells about 40 microns long, flask-shaped, soft, flexible and elastic, normally compressed and somewhat gibbous, about twice as long as broad, widest centrally, obtusely pointed posteriorly, the entire surface more or less covered, often almost concealed, by adherent, irregular and angular sand grains, anterior end constricted to form a short neck-like prolongation, the circular border thickened, expanded, and obliquely truncate, flagellum large, equaling or exceeding the body in length, nucleus not observed, contractile vacuole (?) single, laterally placed near the anterior end, pharaynx apparently extending to near the body centre. Length of Body 51 microns Numerous grains of sand stick to cell surface. Flagellum about cell length or somewhat longer.

Anisonema (a-nice-o-neme-a), heterotrophic euglenid, glides over the substrate, with an anterior flagellum sweeping in front of the cell and with a long recurrent flagellum trailing over the substrate. As is common in the euglenids, the flagella seem to be very thick - especially as we can see here the recurrent flagellum. Occasionally jerks backwards. Common in intertidal sediments. Phase contrast.

Anisonema (a-nice-o-neme-a), a genus of heterotrophic euglenids commonly found in sediments. With one flagellum sweeping from side to side in front of the cell, and with a second flagellum following a hooked curve and then trailing behind the cell. The cells may periodically jerk backwards. Body not metabolic, no mouth visible by light microscopy. Phase contrast.

Anisonema has no chloroplasts. It has two flagella. One projects from the front of the cell and sweeps from side to side, the second flagellum trails behind the cell. This euglenid was collected at Obsidian Creek.

Gliding Anisonema cell, the anterior flagellum is to the top and beats with a sweeping motion, the second flagellum adheres to the substrate and tarils behind the moving cell. Phase contrast microscopy.

Anisonema (a-nice-o-neme-a) is one of the gliding heterotrophic euglenids, common. It has a distinctive pattern of movement, moving forwards with one thicker flagellum trailing and the other flagellum extending in front and sweeping from side to side in front of the cell, and then periodically jerking backwards. This movement is associated with the strong recurrent flagellum which, as it leaves the cell, follows a curve or hook. The genus is defined in part by not having a mouth that is visible by light microscopy, but this cell has clearly been eating diatoms. Differential Interference Contrast.

Anisonema (a nice-owe-knee-ma) acinus Dujardin, 1841. Cell outline is like a grain of barley. Cells are 21 to 40 microns long, 13 to 17 microns wide, flattened with a ventral groove, which diminishes posteriorly. There are about nine longitudinal pellicular grooves on each of the ventral and dorsal faces of the cell. In some cells, the grooves are fine and difficult to see but in a few cells they are deeper. The cells have a chisel-shaped ingestion organelle, which is difficult to observe at times. The anterior flagellum is about 1.5 times cell length and beats freely from side to side. The trailing posterior flagellum is about 1.7 to 3.2 times the length of the cell, is thicker than the anterior flagellum, lies in the ventral groove, and tapers posteriorly. The cells contain diatoms up to 25 microns long and one cell had four diatoms as long as 13 microns The flagellar pocket is located in the left side of the cell and the nucleus is in the right side. The cells glide smoothly, but jerk backwards when changing direction. Commonly observed.

Anisonema acinus Dujardin, 1841. Cell outline is like a grain of barley. Cells are 21 to 40 microns long, 13 to 17 microns wide, flattened with a ventral groove, which diminishes posteriorly. There are about nine longitudinal pellicular grooves on each of the ventral and dorsal faces of the cell. In some cells, the grooves are fine and difficult to see but in a few cells they are deeper. There is debate as to whether this species has an ingestion organelle, it was described without such an organelle, in some cells no organelle is seen, but in other cells otherwise indistinguishable from mouthless cells, a mouth can be seen. The anterior flagellum is about 1.5 times cell length and beats freely from side to side. The cells may eat large particles of food, such as diatoms. The trailing posterior flagellum is about 1.7 to 3.2 times the length of the cell, is thicker than the anterior flagellum, lies in the ventral groove, and tapers posteriorly. The flagellar pocket is located in the left side of the cell and the nucleus is in the right side. The cells glide smoothly, but jerk backwards when changing direction.

Anisonema acinus. Cell observed in freshwater habitats in the vicinity of Broome, Western Australia in September 2003. This image was taken using phase contrast optics.   This work was supported by the Australian Biological Resources Study.

Heterotrophic euglenoid photographed using DIC microscopy. Isolated by M. Virginia Sanchez Puerta from Little Sippewisset Pond, Woods Hole, MA, USA in October 2005

Anisonema ovale Klebs, 1893. Cells are oval, rigid and measure 11 microns long and 7 microns wide. The cell surface is smooth. The anterior flagellum is about the cell length and the posterior one is 1.5 times the cell length. Looks like Protaspis tegere and further study may reveal that this is not really an Anisonema.

Anisonema emarginatum Stokes, 1885. Cells are oval, rigid and 14 microns long. The cell surface is smooth. The anterior flagellum is about 2 times the cell length and the posterior one is about 2.5 times the cell length. Does not look like Anisonema.

Anisonema orbiculatum Lackey, 1940. Cells are 12-25 microns long, circular in outline, slightly rounded above but flattened ventrally, except for a wide, rather deep groove in the median plane. There are two flagella, emerging on the left ventral side through a somewhat crescentic sub-terminal mouth opening into a shallow gullet. Below this also on the left side is a relatively conspicuous nucleus. The short anterior flagellum is thin, about body length, the trailer stout, about twice body length and carried straight bade. No stigma or color. Numerous inclusions, mostly small spheres, in the cytoplasm. Pellicle firm, smooth. Movement principally a steady glide forward. No observed ingestion of food. Reproduction not seen.

Anisonema pusillum Stokes, 1886. Cells are spindle-shaped, rigid and 11 microns long. Dorsally convex and ventrally concave. The anterior flagellum is about the cell length and the posterior one is about 3 times the cell length. Although initially assigned to the genus Anisonema, it seems improbable that this assignment is correct.

Heteronema (het-er-owe-knee-ma) a small heterophic euglenid . Its euglenid affinities are evident through the pellicular striations and the thick flagella. The flagella look thick because, as with most euglenids, there is a supplementary element lying alongside the axoneme within the flagellum. Phase contrast.

Heteronema (het-err-o-knee-ma), a genus of heterotrophic euglenid flagellates. With two flagella, both of which are thicker than usual flagella. One flagellum projects anteriorly, one trails behind or to the side of the cell. With an ingestion organelle. The grey ovoid region to the right is the nucleus. Phase contrast.

Heteronema (het-err-o-knee-ma), a genus of heterotrophic euglenid flagellates. With two flagella, both of which are thicker than usual flagella. One flagellum projects anteriorly, one trails behind or to the side of the cell. There is an ingestion apparatus, which included two stiff refractile rods that are used to manipulate food into the mouth. They can be seen just posterior to the insertion of the anterior flagellum. Differential interference contrast.

Heteronema (het-err-o-knee-ma), a genus of heterotrophic euglenid flagellates. With two flagella, both of which are thicker than usual flagella. One flagellum projects anteriorly, one trails behind or to the side of the cell. With an ingestion organelle. Phase contrast.

Heteronema (het-err-o-knee-ma), a genus of heterotrophic euglenid flagellates. Like other genera in the same taxonomic area (such as Peranema), the body is very flexible and can squirm (i.e. is metabolic). Common in freshwater and marine ecosystems, consuming bacteria, detritus and other protists using a small mouth located near the front of the cell. Quite variable in appearance. Differential interference contrast.

Heteronema, a euglenid flagellate, colourless and usually with an ingestion apparatus (not visible here). Distinguished from Peranema because the recurrent flagellum does not adhere to the body but trails behind the gliding cell. From Lake Donghu, China. Phase contrast micrograph.

Gliding cell, the anterior flagellum is to the right, the recurrent flagellum is shorter and trails behind the gliding cell. Phase contrast microscopy.