Maritime tardigrades (VIII) - one step backwards

Okay, we have moved too fast. In the beginning our plan was to deliver just one or two issues on maritime tardigrades. But meanwhile we have collected some historic and modern literature and we would like to share our findings with you. But be warned that a husband or wife might become nervous at the beach when the partner is going to spend endless hours on the screening of sand grain samples.

We will not present the outstanding anatomic drawings by Ernst and Eveline Marcus here because they are still under copyright. But there exists an older publication by the French biologist Lucien Cuénot which can be found in antiquarian bookshops and which is being offered as a free pdf online as well.

Cover page of Cuénot's classical work "Tardigrades" (1932).
The nice and well-illustrated booklet might be a rare guest in antiquarian bookshops but meanwhile it is available online as well ... see below.

Thanks to the "Fédération Française des Sociétés de Sciences Naturelles" and its web campaign "Éditions Faune de France" we can look at a copy of Lucien Cuénot's "Tardigrades" and it is free!

Just go to the Fédération, choose item "Faune n° 24" and you will be offered to download the complete Cuénot (5.2 MB). On page 32 you will find a nice diagram with the complete anatomy of Batillipes which you should print out for reference. Here is our translation of the French comments, with a little bit of additional information from our side:

A

Cirrus lateralis, two long bristles, on the left and right side of the head.

an

Anus, difficult to distinguish in the light microscope (a small slit).

c

The Clava (from Latin: cudgel, club), an almost cylindrical long body, sometimes twisted, sometimes with one or several constrictions, with an apparently complex inner structure, interpreted as a chemo-sensors by nowadays' scientists.
Batillipes has a Clava and a Cirrus lateralis on a common base.

cb¹

Two symmetrically oriented Cirri interni (cirri laterali interni) with nerve fiber connection to the brain.

cb²

Two symmetrically oriented Cirri externi (cirri laterali externi) with nerve fiber connection to the brain.

cc

Tail, the geometry of which might vary individually and between species. If present it is - as a rule - an important criterion for species determination: Batillipes acaudatus (without tail), Batillipes bullacaudatus (with thick tail end) etc.

cr

Cirrus medianus, a single bristle on the tardigrade back, oriented upwards, possibly a water level sensor. Nerve fiber connection to the brain.

D

Two Cilia D, on the left and right side of the body (without inner nerve fibers).

e

Small lateral spurs, not always present, protruding from the lateral lobes between the third and fourth leg pair. The lobes are important for species characterization but only faintly visible in the diagram.

ep¹ ... ep⁴

Legs spurs, sometimes difficult to discern or missing.

g

Testicles, see contour line, above the stomach-intestine-system, might fill the complete back volume of a male tardigrade. Can be easily seen in side view.

gb

Mouth gland (saliva gland), which serves as well to renew the mouth parts after moulting.

gv

Ventral ganglion, classical "rope ladder"-type ganglion below the mouth tube, ventrally protruding to the hind end of the body, with ganglion nodes. Similar to the ganglion system of Milnesium tardigradum.

i

Intestine, with (typically) six lobe pairs. Mostly filled with brown algae residues, little internal structure visible.

o

Mouth opening

oc

So-called eye-spots, resembling eyes, but considered as lipoid deposition without sensoric function.

og

Gonoporus

pb

Papilla cephalica (or Secundary clava), only weakly developed in the case of Batillipes. (Sensory?) function unknown.

so

Big Brain with brain lobes, situated above the mouth tube.

vs

Gonads, with symmetric ducts. The symmetric ducts are characteristic for the male tardigrade and allow a quick distinction between males and females already at moderate magnifications. The male hind body looks perfectly symmetrical whereas the female ovoduct is single-asymmetrical, passing either on the left or right hand side of the intestine and often bearing a fully developed egg at its end.

The drawing is phantastic but you might want to have a look at the real thing as well? Please keep in mind that all those tiny anatomical details are extremely difficult to photograph in good quality. So we are quite proud to be able to present the following photomicrograph of the Batillipes head multi sensor system:

Head of a Batillipes tardigrade, as seen from below. Explanations:

-- Cirrus A (A), long, strongly blurred, in the background, barely visible
-- Chemo-sensor clava (c). Please note that the clava has an interior structure
-- the external and internand Cirrus medialis pairs (cb² bzw. cb¹), note the nerve fibers inside
-- two very small secundary clavae (pb)
-- and the position of the Cirrus medianus (cr) on the tardigrade back, not visible here

Strongly magnified, oil immersion objective. Image width ca. 50 µm.

Literature

Gallo D'Addabbo, M.; D'Addabbo, R.; de Zio Grimaldi, S.: Redescription of Batillipes dicrocercus Pollock, 1970 and Revision of the Genus Batillipes (Tardigrada, Heterotardigrada).
Zoologischer Anzeiger 239 (2000) p. 329 - 339.
[Comment: the most recent genus Batillipes review we have come across]

Reinhardt Kristensen: On the fine structure of Batillipes noerrevangi  Kristensen, 1978 (Heterotardigrada). Part 3. Spermiogenesis. p. 97 - 105. In: Barbara Weglarska (Ed.), 2nd International Symposium on Tardigrades 1977. Krakow 1979.
[Comment: an excellent species characterization with nice illustrations]

Ernst Marcus: Zur Anatomie und Ökologie mariner Tardigraden. Zoologische Jahrbücher, Systematik, Bd. 53 (1927) p. 487 - 558.
[Comment: in our opinion even tody the ultimate über Batillipes and Echiniscoides reference. In German language]

Jeanne Renaud-Mornant und Leland W. Pollock: A Review of the Systematics and Ecology of Marine Tardigrada. In: Neil C. Hulings (Ed.), Proceedings of the First International Conference on Meiofauna. Smithsonian Institution Press, Washington 1971.

Ferdinand Richters: Tardigraden-Studien.
In: 40. Bericht der Senckenbergischen Naturforschenden Gesellschaft,
II. Teil: Wissenschaftliche Mitteilungen. p. 28 - 48 and 2 tables. Frankfurt am Main 1909.
[Comment: the first (!) photomicrograph of a Batillipes tardigrade]

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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