biologe

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Tag: microscopy

Oribatida mites: Fast runners and slow crawlers

Microhabitats often consist of a complexity of organism species. Under suitable conditions, samples can be kept „alive“ for months and even for years by regularly adding moisture and organic tissue, in case of my sample of this footage: patato pieces.

 

 

Mites of the Oribatida and their different ways of locomotion. Copyrights: Stefan F. Wirth, Berlin April 2019. Please give the video a like on youtube too.

 

Soil samples from island Norderney

 

This soil sample was collected in summer 2018 on the North Sea island Usedom during my participation at the „Geo Tag der Natur“. It contained several specimens of the predatory chilopode Lithobius sp. and pieces of rotting wood, moss and forestground, everything collected under rotting treetrunks and tree branches. The samples additionally contained the carabid beetle Pterosticus cf. niger and ants of genus Lasius. Samples were collected in a small forest area with wetland aspects. The soil quality was rather moist.

 

Astigmatid mites

 

I later added potato pieces and regularly some water droplets to the sample with still living big arthropods/ insects. After some weeks, specimens of the astigmatid mite Acodyledon cf. schmitzi developed on dryer areas of the potato pieces. These mites were presumably phoretic associates of the carabid beetles. They died out after several months, after the sample had dried out a little bit and may be due to changes of the room temperature during winter time.

 

Oribatida

 

Now, almost a year later, the micro habitat is inhabited by mites of the Oribatida in greater numbers of specimens of at least three species: Nothrus sp. (genus not yet clarified), Nothrus palustris (already found for the first time shortly after the sample collection) and a species of Phthiracarida.

 

Locomotion and biodiversity

 

Purpose of the short film is to show different organisms, cultured after about a year in this sample: mites, nematodes, collembolans and microorganisms, fungae and bacteria. Of the bigger arthropods/insects, only one Lithobius species survived until now.  Also the diversity of ways of locomotion in different oribatid species is emphasized: There are slow crawlers (Nothrus) and fast runners (Phthiracarida).

 

Berlin, April 2019, Copyrights Stefan F. Wirth

Microscopic wrack inhabitants: Mites (Ameronothridae), Protozoans, nematodes and Dipterans

Decomposing detritus (mostly dead algae debris) of marine organic material, laying onshore more or less close to the water line, containing seaweed or cadavers of aqatic animals, is named wrack. Wrack can appear under different kinds of ecological circumstances. In case, it would be in permanent contact with sea water, it might be mostly decomposed by marine organisms. But due to different reasons, wrack can land apart from a permanent sea water contact or even no sea water contact at all any more.

Here mostly terrestrial organisms with a tolerance for salty conditions would inhabit and decompose this piece of detritus. Sandhoppers (Cristacea) are known to switch between wracks of different conditions. They can for example carry mites or nematodes from one wrack habitat to another. Dead organic material generally always needs to be decomposed by living organisms, otherwise the whole ecological system would be harmed.

 

A specific kind of micro habitats

 

A small habitat, which would dry out after a while and thus exists only for a limited time, is called ephemere biochorion. Organisms being adapted to live there, must have adaptations, to leave their habitat by time to avoid desiccation. One option is a life strategy, which is named phoresy. Weaker organisms, unable to desperse themselves efficiently use other animals, such as winged insects, to take a ride on them to new habitats with suitable conditions for a development. Generally phoretic organisms can for example be represented by different groups of mites (e.g. Uropodida, Gamasina, Tarsenomidae, Scutacaridae, some Oribatida, Astigmata) and nematodes (Rhabditida).

 

Mites and nematodes

 

In case of wrack, decomposing close to the waterline, but without or only occasional water contact, Pellioditis marina (Nematoda, Rhabditida) is for example known as phoretic inhabitant along German coasts. Worldwide, crypitical sibling species of P. marina were meanwhile discovered. Depending on the exact situation of the wrack, also aquatic nematodes could appear there for a while. I couldn’t determine the nematode in my footage unfortunately at all, because I did not prepare slides of them enable a larger microscopic magnification. Phoretic mites can be associated with sand-hoppers (Amphipoda, Crustacea) and thus appear in wrack. Mites of the Histiostomatidae (Astigmata) were for example discovered in such a context by some researchers.

 

Mites of the Ameronothridae (Oribatida), sand-hoppers and dipterans

 

I so far never found them randomly, but also didn’t explicitely seek for histiostomatid species until now. My sample did not contain any Astigmata or I at least didn’t find them. Common inhabitants of decomposing wrack are oribatid mites of the Ameronothridae. This taxon with a worldwide distribution is charaterized by specific adaptations to deal as terrestrial organisms with (partly extreme) salty marine conditions. They are mostly algae feeders. Some species are known to appear in wrack. The sample, which I collected in context of the so called „Geo Tag der Natur 2018“ (Geo (journal) day of nature) in Norddeich Mole (East Frisian coast of Germany) contained many specimens (ca. 40, sample size of about 20×20 cm) of the Ameronothridae-species Ameronothrus sp.. My footage shows only one living specimen, as all had died until I began my filming activities.

Inhabitants of decomposing algae tissue along a beach at German North Sea, all copyrights Stefan F. Wirth

 

But I preserved several dead specimens for scientifc purposes. Ameronothridae might, according to literature, use phoresy via birds, but also might disperse themselves over smaller distances, due to their well developed cuticle, protecting against desiccation, and their rather fast locomotion abilities. Larvae of different species of flies (Diptera) developed inside my sample and hatched under my laboratory conditions after about two weeks. They intensively contributed to a fast decomposition of that organic marine tissue. Sand-hoppers were by the way not found at all.

 

Bacteria and protozoans

 

Bacteria are most important decomposers. But the function of protozoans (here e.g. Ciliata) in regard to the process of wrack degradation, which could still be isolated alive after about two weeks of decomposition,  is unknown to me. My sample was found almost on top of a dike, meters away from the highest tide in that area and consisted mostly of the seaweed Fucus vesiculosus.It also contained sea gull feathers.

 

Berlin/ Norddeich Mole June/August/November 2018 Copyrights Stefan F. Wirth

A scarab beetle’s larva and pupa: habitats for mites and other organisms

The micro-world is complex. Its habitats intertwine themselves, some even are unusual, because they are formed by single animal individuals. An example is a holometabolic insect, here the tropical rose chafer Eudicella colmanti. The larvae of my specimens are covered with deutonymphs of an astigmatid mite (Acaridae, eventually Acarus sp.).

This makes the beetle larva to a habitat for these mites, although the mites in this case don’t feed or reproduce there. They instead are „only“ passengers on their transportation to a new „real“ habitat, where they become adult, feed and reproduce. This strategy to be carried by other organisms from one living place to another is called phoresy.

The situation in my terrarium might be artificial in the sense that mites are putatively not of tropical origin as the beetles (reared in Germany) and thus do not originally „belong“ to the beetle species. The mites might have reached into the terrarium via fruit flies or similar native organisms or via the terraria of the online shop, where they were bought. But the mite deutonymphs show a distinct affinity for adult beetles and their larvae nevertheless, which they attached in great numbers (not the pupa). The microscopic footage of the mite deutonymphs contains activities of their genital openings, located close to the sucker plates on their undersides.

They occasionally open and close and discharge secretions or water. This might be due to osmoregulation and/or in order to prove the adjacent sucking structure with moisture for a more stable hold.

The larva after some months built its pupa chamber, consisting of soil particles and larva secretions. Tese pupa chambers offer on their outer sides obviously enough nutrients for collembolans, which appeared there in greater numbers, especially on an older chambers with its pupa waiting to hatch. Mites of the Gamasida and tiny annelids could also be observed there. The video consists of macro fotage and microscopic footage, all recorded in 4K and rendered in an uncompressed quality.

 

Berlin, December 2017/November 2018, copyrights Stefan F. Wirth