Tag Archives: #Amphipod thursday

Scavengers in the ocean

Lysianassoid amphipods from a trap in Raudfjorden, Svalbard. Photo: AHS Tandberg

Most animals are sloppy eaters. They have their favourite piece of food that they go for, and then they leave the rest. This allows for others to pick up where others leave. One of the laws of ecology is that “there is no such thing as an empty ecological niche”. That can be translated to “where there is a food-source (or a place to live) someone or something will use that food-source (or place to live). And that gets us to the sloppy eaters out there, and not least the animals picking up after all the sloppy eaters.

From the pigeons crowding under your cafe-table for your panini-crumbs to the rats in our sewers, our “local scavengers” tend to be animals we feel slightly uncomfortable around. Is it different with the scavengers we dont see so often? It does not seem that way. Vultures  are not the most popular birds, even the word “vulture” has a negative connotation – and we mainly use it in its non-bird meaning.

How about the scavengers of the sea? As on land, we have many different animal-groups that can be classified as scavengers. Many of the marine scavengers are invertebrates (even if some fishes also scavenge). Let us look at the scavenging Lysianassoid amphipods. Are these as little loved in our world as the rats and vultures seem to be?

A typical lysianassoid amphipod. Photo: AHS Tandberg

Lysianassoid amphipods can mostly be distinguished from other amphipods by their “telescope-like” antennae: a very fat inner article with the two next looking like a collapsed old fashioned radio-antenna; two short rings. We know that the antennae of crustaceans are often used to “smell” things in the water – food or mates or possibly even enemies. It is not thought that the radio-antenna-shape of the Lysianassoid antenna specifically has to do with being a scavenger, as other amphipods and indeed several other crustaceans not having such an antenna are also scavengers. But most Lysianassoids have that antennae, and it makes for an easy first-sorting for the scientist. (Getting further – towards a genus, or even species name on the other hand, is not so easy).

Other general traits in most Lysianassoids, are the smooth exterior, and their high swimming abilities. Both are good if you need to get to some leftover food-source fast, and to “dive” into the food-source while not getting stuck through the entry.

Leftovers of bait (polarcod) after 24 hrs in the trap. Not much left for dinner… Photo: AHS Tandberg

And this is where many Lysianassoids loose out when it comes to human appreciation. They seem to love to scavenge on fish caught in fishnets and traps, and both professional and hobby fishers don’t like to share their catch. We dont think it is very appetising to find our fish-dinner “infested” by non-fish. I am quite sure the scavengers being pulled up with their lovely find of dead or dying fish also are not pleased with having to share their dinner with us.

Lysianassoid scavenging amphipods are the focus of our NBIC-financed project NorAmph2. Here, we will collect and register what different species are present in Norway, and we will try to barcode them. These are quite tricky animals to identify properly, but luckily we have teamed up with the best lysianassoid-expert we know – Tammy Horton from the National Oceanography Centre in Southampton, UK.

We use baited traps to collect: put some lovely, smelly fish out there and see who comes to dine. So far, we have collected from Svalbard in the north to Kong Haakon VIIs Hav in the south, and from the intertidal to the deep. They are often many, and the size-variation is great. We look forward to continuing finding out what species we have, and to see if what morphologically seems one species really is (only) one species genetically. (This previous blog-post (in Norwegian) tells the story about one scavenging amphipod that turned out to be 15 (or maybe even more!) separate species)

Anne Helene

Why study boring amphipoda and other strange taxa?

Bircenna thieli seen from the front and the side. SEM photo, Fig 6 in Hughes and Lörz, 2019.

This question (or a version of it) is something a lot of us taxonomists are faced with quite often when we try to explain what we do for a living. And I do understand the need to ask – couldn´t our talents be used better doing something it might be easier to understand the use of? We think the study of taxonomy is higly important, and does bring about useful knowledge for the world. Therefore, we have several taxonomic projects in our group, and we write about them here in the blog. (If you read norwegian, you can read about our projects here)

 

March 19th was the world Taxonomist Appreciation Day – a day we have “celebrated” since 2013. Why do we need this day? Taxonomy is the science of naming, defining, describing, cataloguing, identifying and classifying groups of biological organisms. We do this in labs and on fieldwork, and the natural history museums (these days represented from our home offices) have a special responsibility for this work, since one part of the formal description of a taxon is to designate a type and store that in a museum collection. We will come back to the importance of types in a later blog here.

Terry McGlynn, the professor and blogger who initiated the Taxonomist Appreciation Day wrote: ” I want to declare a new holiday! If you’re a biologist, no matter what kind of work you do, there are people in your lives that have made your work possible. Even if you’re working on a single-species system, or are a theoretician, the discoveries and methods of systematists are the basis of your work. Long before mass sequencing or the emergence of proteomics, and other stuff like that, the foundations of bioinformatics were laid by systematists. We need active work on taxonomy and systematics if our work is going to progress, and if we are to apply our findings. Without taxonomists, entire fields wouldn’t exist. We’d be working in darkness.”

Every year a large number of new taxa are described – last year almost 2000 of the new species described were marine. March 19th every year, the World Register of Marine Species (WoRMS) and LifeWatch publish their favourite 10 marine species described in the previous year, and this year – corona-shutdown and all – was no exception.

All ten new species are fun, beautiful and remarkable – but Polyplacotoma mediterranea Osigus & Schierwater, 2019 deserves special mentioning. P. mediterranea is the third species described ever in the phylum Placozoa – who are viewed as one of the key-taxa to understand early animal evolution. They were first described in 1883 (by Schulze), and the name Placozoa indicated what they looked like: small (around 1 mm for the largest of the specimens) platelike animals. 2018 saw the second species of placozoans described – genetically, as it was impossible to separate morphologically – but then our new placozoan came – and it is 10mm large, is branched, and has its natural habitat in the mediterranean intertidal! Phylum Placozoa will never be the same again, and our understanding of the early evolution of animals has become even more interesting.

 

What then about the boring amphipods? Or course they are not boring as in saying they are dull! The “boring amphipod” Bircenna thieli Hughes & Lörz, 2019 bores in the sense that they excavate tunnels into the stem of the common bull kelp Durvillaea potatorum (Labillardière) Areschoug, 1854 in the intertidal and shallow waters by Tasmania.

Bircenna thieli has a head almost like an ant, and a quite unusual shape of its back-body. Fig 8 from Hughes and Lörz, 2019

Their head has an ant-like ball-shape unlike many other amphipods where the head is more ornate or has a visible rostrum, but the exciting morphology comes at the other end of the animal – where the telson and last segment have structures never seen before in amphipods, and structures that only other vegetation-boring amphipods show.

So why do we think describing tiny animals, plants, fungi, bacteria and other organisms is so important? Let us ask you back: how can you appreciate what you have and care about what might be lost if you dont know who they are?

Anne Helene

(this post was written March 19th, but posted later..)


Literature:
Eitel M, Osigus H-J, DeSalle R, Schierwater B (2013) Global Diversity of the Placozoa. PLoS ONE 8(4): e57131. doi:10.1371/journal.pone.0057131

Hughes, L.E.; Lörz, A.-N. (2019). Boring Amphipods from Tasmania, Australia (Eophliantidae: Amphipoda: Crustacea). Evolutionary Systematics 3(1): 41-52. https://doi.org/10.3897/evolsyst.3.35340

Osigus, H.-J.; Rolfes, S.; Herzog, R.; Kamm, K.; Schierwater, B. (2019). Polyplacotoma mediterranea is a new ramified placozoan species. Current Biology 29(5): R148-R149. https://doi.org/10.1016/j.cub.2019.01.068


Do you want to find out more about Taxonomist Appreciation Day or about all the 10 exciting species?

Ten remarkable new marine species from 2019

Today is Taxonomist Appreciation Day!

A compendium of taxonomists on ORCID

and not least –  you can still follow the #TaxonomistAppreciationDay on Twitter (and be prepared for 2021!)

Door #20 The Hitchhikers Guide to the Ocean

The sea is for most of its inhabitants a vast place where danger can get to you anywhere. This might be especially true when you are one of those small and mostly harmless species spending your life slowly swimming around, minding your own business (eating and reproducing), somewhere in the upper 200m or so of water. Because there are many big-mouthed and possibly big eyed animals out there that think you might be one of the best things there is to eat.

Hyperiella antarctica with Spongiobranchaea australis. Photo: C Havermans, AWI.

For the small pelagic (living in the open ocean and not close to the sea floor) amphipods in the suborder Hyperiidea this is one of the dangers of everyday life. The genus Hyperiella can be found in the Southern Ocean, and one of their main predators are the icefishes (Nototheniidae). So what do you do when you are a small and quite tasty animal that is not a very fast swimmer and there are a lot of fishes out there to eat you?

Don´t panic!

Hyperiella antarctica with Spongiobranchaea australis (a and b) and Hyperiella dilatata with Clione limacina antarctica (c). Figure 2 Havermans et al 2018.

Two of the three Hyperiella-species have found a quite ingenious solution. They hitchhike with a group of other small slow-swimming pelagic animals – pteropods. Pteropods (from the greek “wing-foot”) are sea snails (gastropods). Hyperiella australis pics up a life with Spongiobranchaea australis, and Hyperiella dilatata hangs out with Clione limacina antarctica. Both pteropods are from the group we call Sea Angels (Gymnosomata), and in a way they are saving angels for the amphipods: the ice fish don´t eat these strange couples. Why?

It seems the pteropods have developed a chemical protection against predation. They obviously taste extremely bad, for observations of icefish trying to eat the hitchhiking amphipods together with the pteropods result in them both being spit out again. Most times, the fish would see what it thought was good food, and then swim away when they discovered what they were almost eating. Not so very strange, then, that Hyperiella are holding on to their colleagues for their life!

 

 

Clione limacina antarctica. Photo C Havermans, AWI.

It might not be hitchhiking after all, but rather kidnapping – or brute force. The amphipods hold on to the pteropods with their to-three hindmost pairs of legs, and keep the sea angel on their back – much like a backpack. Observations are that they are repositioning them there all the time – almost like kids running with bumpy backpacks on the way to school. They don´t even let go when the researchers preserve them!

Hyperiella antarctica with Spongiobranchaea australis backpack. Photo: C Havermans, AWI

What this treatment do to the pteropods we still don´t know. But it does not seem they are able to eat very much when being held hostage as chemical defence-backpacks. That may not be the biggest problem in a short time-scale – their Arctic relatives have been shown to survive almost a year without food. What happens when they really get hungry we do not know. The amphipods are still able to feed, even though the pteropods can be up to 50% of the amphipod size. Maybe the pteropods do some of the swimming for the amphipods?

This behaviour is much more common close to the coast than in the open sea: close to the McMurdo area, 75% of the Hyperiella were seen hitching with a pteropod. Now we know that this pairing can be found in the open sea, and maybe is it more common that we think. It is not the first thing we have looked for so far when examining samples. When the University Museum of Bergen joins the Norwegian Polar Institute and the Institute of Marine Research to the Southern Ocean in the austral autumn this coming March, we will make a special effort to search for such collaborators.

Anne Helene


Literature

Havermans C, Hagen W, Zeidler W, Held C, Auel H 2018. A survival pack for escaping predation in the open ocean: amphipod-pteropod associations in the Southern Ocean. Marine Biodiversity https://doi.org/10.1007/s12526-018-0916-3

McClintock JB, Janssen J 1990. Pteropod abduction as a chemical defence in a pelagic Antarctic amphipod. Nature 346:424-426.

 

 

Door #13: The story you can find in a picture…

It is often said that a picture is worth a thousand words. We use both drawings and photos (and sometimes even films) when we are describing species, and without these illustrations, we would often have to make guesses as to what the author meant when describing the morphology of the species in interest.

Generally, the old literature did not make as much room for illustrations as we have the possibility to do today – the printing often needed entire plates (pages) produced much in the same way an artist still produces a carved or engraved print today – and when there is a plate in an old publication it quite often is a piece of art. But – the plates (figure-pages) were expensive to print (even more than the text-pages), and thus often limited to the bare necessities.

There are exceptions! C. Spence Bate and J. O. Westwood (both with so many letters behind their names that they included “etc” at the front page) commissioned J van Voorst in London to print  their book “ A History of the British Sessile-Eyed Crustacea” in two volumes. The first came in 1863, the second in 1868.

And it is enjoyable reading. “Sessile-eyed” crustaceans are explained as those crustaceans who do not have stalked eyes (as for instance the crabs and shrimp have) and it was used to classify crustaceans since Leach in 1814 named the gruop “Edriophthalma” (sessile-eyed in greek). This group included Isopods and Amphipods – but the discussion was still going strong about what taxa should be included in these groups, and how they were “connected” with the other crustaceans. The gentlemen Bate and Westwood decided to describe and discuss each of the species they knew of as sessile-eyed in Britain. This would be a basis for the further discussions on higher groupings. Interspersed in the text are figures of the species and special morphological structures they are discussing, making the book easy to follow and understand. An introduction on the general morphology, physiology, reproductive biology and geographical distribution of the sessile-eyed crustaceans, the rest of part 1 discusses the Amphipoda.

They really mention every species they have come across – ever – from anywhere in Britain. Sometimes that may be one single specimen of what they think must be a new genus and species (and that seems to have been forgotten later),  and in addition to the drawings of the morphology they add a drawing of the location where it was found.

It is at the end of volume 1 that we come to the picture that captures my imagination the most. Under the discussion of Corophium longicorne  (accepted name: Corophium volutator) they discuss the extraordinary strong second antennae of the species:

“The inferior antennas are very powerful, and in the male are longer than the animal itself; the pentultimate joint of the peduncle being armed upon the inferior distal extremity with a strong tooth, which appears to assist considerably in holding any object when the extremity of the antennae is folded upon itself; this organ appearing to possess the strongest prehensile power, and being no doubt used as a weapon of offence in its battles with other animals in its struggle for existence.”

Corophium are known from sandy and muddy shores – where they “dwell in small tubular galleries, excavated in the mud, over which the tide flows and ebbs”.  They go on to discuss their ecology – as predators of other shore-living invertebrates.

They cite “Rambles of a Naturalist” of Quaterfages on the feeding habits of this fierce amphipod:
at about the end of April they come from the open sea in myriads (they are called Pernis by the fishermen of the coast of Saintoge) to wage war with the annelids, which they entirely destroy before the end of May; they then attack the mollusca and fish all through summer, and disappear in a single night about the end of October, and return again the following year.

Bate and Westwood do not follow up the story from Quaterfages with any other documentation, but they ask their readers to send them more data if they have. Corophium volutator was described already in 1766 by Pallas, and is found on sandy or muddy beaches all around the North Sea. Maybe you will see a battle between a Corophium and an annelid? All later research into this species and the close group of related amphipods show us that these are detrivorous (eating organic matter from the mud where it lives). We might never know what inspired the fishermen that Quaterfages talked to. But if you see something like this, we would really like to know!

-Anne Helene

Literature:
Bate CS, Westwood JO.1863. A history of the British Sessile-Eyed Crustacea. Part 1. John van Voorst, London (Paternoster Row). 580 pp.

Door # 6: The key to the question

We often say that without knowing the species you examine, you really can’t know a lot about whatever it is you are examining. But how do you get from knowing for example “this is an amphipod” to knowing “this is Amphilochoides serratipes”?

Three different Amphilochidae from Iceland

Most researchers would usually stop at the “this is an amphipod”-stage, and many specialists  would call it a day at “this amphipod belongs to the familily Amphilochidae”. but then there are the one or two researchers who have gone on to specialise in this family (I think there are three of us in the world at the moment).

But finally – those days are over!
As a special gift on this Nicholaus-day when all German colleagues get a special gift from St Nicholaus (who is Father Christmas) we present to all of you – regardless of nationality or faith:

The interactive and illustrated key to the NorthEast Atlantic species of Amphilochidae

The key is a product of a collaboration between the NorAmph-project and the German-lead IceAGE project that examines benthic animals around Iceland, and the technical production and web-hosting of the key is from the Norwegian Taxonomy Initiative (Artsprosjekt) (who – we have to say – also have financed the NorAmph-project!) Hurrah for a great collaboration!

Figure 14 from Tandberg et al

You might still wonder what an Amphilochid amphipod is?

The family Amphilochidae are amphipods that are quite small (1-6mm in length) and quite stout. They are not extremely good swimmers, though much of that can be from their small size – and from their short appendages. They can be found all over the world, and are common at many depths in our cold waters. Even though they are small and easily overlooked, they sometimes occur in relatively large numbers, and can contribute significantly to both the biomass and diversity of a sample. They have been found on hydrothermal vents at the southern part of the Mid-Atlantic ridge, and some have been found as loose associates of other invertebrates.

Also – they are quite cute, don’t you think?  Good luck with the identification!

-Anne Helene

Literature:

Brix S et. al. 2018. Amphipod family distributions around Iceland. ZooKeys 731: 1-53. doi: 10.3897/zookeys.731.19854

Tandberg AHS, Vader W 2018. On a new species of Amphilochus from deep and cold Atlantic waters, with a note on the genus Amphilochopsis (Amphipoda, Gammaridea; Amphilochidae). ZooKeys 731: 103-134. doi: 10.3897/zookeys.731.19899