Library > Theme Room > Interesting movement I

Solitary journey

The body of this flagellate is long and thin, and its single flagellum extends forward and remains stiff, except for actively vibrating the very tip. Occasionally the flagellate contracts its body to change directions, but usually it travels in a straight line.

Commentary by Prof. Yuji Tsukii, Hosei University
This flagellate belongs to genus Peranema, most likely Peranema trichophorum, but there is scarce research available about this genus.

In the field, we can see flagellates in the Peranema genus that are clearly different from P. trichophorum, but unfortunately names have not been assigned to all the individual species.

Sampling Date : 08 August 2009

Sampling Site : Hirose River A  Google Map

A sudden change of direction

This is a comparatively large oval flagellate with two flagella. The shorter flagellum moves actively at the front, while the longer one trails behind. Usually the orgtanism travels in circles at a leisurely pace, but it is also capable of suddenly revising directions. We can see it passing easily between aggregates thanks to its thin, flat body.

Commentary by Prof. Yuji Tsukii, Hosei University
This organism belongs to genus Anisonema.

There is not enough information to determine its species.

In general, Anisonema acinus can exhibit several cell size and either soft or rigid long flagella extending backward, so it is uncertain whether these organisms are the same or not.

The Anisonema in this video is 100μin length, which is much larger than the cell length reported in reference books.

Therefore it is better to classify the organism simply as Anisonema sp.

Sampling Date : 03 July 2009

Sampling Site : Hirose River B  Google Map

Diatoms and algae playmates?

One by one numerous diatoms approach a long chain of algae that is moving in a leisurely arc. Sometimes the diatoms snuggle against and push or poke the algae, but the algae chain continues its journey as if it doesnt care.

Commentary by Prof. Yuji Tsukii, Hosei University
This blue-green alga belongs to genus Oscillatoria.

Many species are included in genus Oschillatoria, and their identification is tricky.

But judging from the unique shape of this organism, it might be Oschillatoria jovis.

The cell-size of O.jovis is reported to be 3.4~4.2μm in width, and if the width of this organism is similar, the organism is likely to be O.jovis.

The diatoms passing by Oschillatoria might be a species of genus Navicula, but this is difficult to determine because there are so many small diatoms with a similar appearance.

Diatoms are usually difficult to identify without observing their shell pattern using a scanning electron microscope or a high-resolution optical microscope. To do this, it is necessary to remove cell material from the shell through a chemical process.

Sampling Date : 08 August 2009

Sampling Site : Hirose River A  Google Map

Mysterious behavior of Bacillaria

Bacillaria is a colony in which numerous individual diatoms are connected. The individual diatoms are lined up side by side, which looks like a window blind when the colony is contracted. When the colony stretches out, the diatoms are connected nearly end to end in a long chain-like structure. Bacillaria usually moves in a straight line when extended, but can change directions freely when contracted. Various small diatoms, aggregates and crystals are stuck to Bacillaria and move along with it.

Commentary by Prof. Yuji Tsukii, Hosei University
This organism is definitely a type of Bacillaria, possibly Bacillaria paxillifer.

Sampling Date : 02 July 2009

Sampling Site : Hirose River A  Google Map