Myrmecomorphy in action!

Sunday the 15th October was the date of the Amateur Entomologists’ Society field meeting at Rye Harbour Sussex Wildlife Trust reserve. It’s not often that I do a focused invertebrate hunt at this time of year, so I was looking forward to seeing what we found.

The field meeting was unexpectedly good on the arachnid side of things. I had no idea that the reserve was so rich in numbers and species of spider. We spent most of our time in a compartment of saltmarsh and shingle, where the shingle was really shallow. The layer of shingle was about two stones thick, and the soil beneath it was compact. This meant that the spiders could not escape deeper into the shingle as they would at most shingle sites.

One of the highlights of the field meeting spider-wise was the fantastic Myrmarachne formicaria. As the scientific name suggests, this species of spider is an ant-mimic (the prefix ‘myrm’ means ‘ant’ and a formicarium is an ant farm). The mimicry of ants in the animal kingdom is known as ‘myrmecomorphy’ and is quite common across a number of invertebrate orders. Invertebrates that are known to be ant mimics include young grasshoppers, true bugs (Hemiptera), flies, beetles and of course spiders.

But why do so many invertebrates mimic ants? Ants are known among the predators of invertebrates to be aggressive or distasteful, so they are avoided. And the predators will also avoid any insects that look like them, but lack any means of defence such as the young grasshoppers. This is known as Batesian mimicry, as it was first described by H W Bates. Some ant mimics have even gone as far as to mimic the ants chemically as well, by emitting ant-like pheromones, which is referred to as Wasmannian mimicry.

However, Myrmarachne formicaria may mimic ants for a different reason. It is thought that some spiders mimic ants not only for protection against predators but also so that they can hunt the ants themselves. Ants will overlook the spiders as one of their own colony, giving the spider the perfect opportunity for a meal. This type of mimicry is aggressive mimicry. As you can see from the photo below, the spider has a long abdomen, which helps it to resemble an ant.

Myrmarachne formicaria male by Evan Jones

Myrmarachne formicaria, photo by Evan Jones, one of the field meeting attendees.

Myrmarachne formicaria really was a fantastic sight, and I hadn’t personally seen anything like it before. It was fascinating to learn how and why so many different invertebrates mimic ants. The sheer number of ant mimics must indicate that ants are one of the most successful of all invertebrates.

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There’s a fungus on the Town Hall Clock!

If you’ve read my latest post you would know that I am a regular participant of #wildflowerhour. During last week’s Wildflower Hour there were predictably more photos due to the increase in flowering plants as spring progresses. Among these flowering plants was the easy-to-overlook Moschatel (Adoxa moschatellina), which I had never recorded before.

So last week I set out with a picture of Moschatel in my mind so that if I did come across the species I would recognise it. Yesterday I visited Pulborough Brooks RSPB reserve in West Sussex and I did both of those things: I came across a couple of large patches and I recognised it!

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The flower head. You can see that it is cube-shaped, which is what lead to the alternative vernacular name of ‘Town Hall Clock’.

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The whole plant

As you can see from the above photographs, Moschatel is not a hard plant to miss. Its flower heads are only slightly lighter than the leaves and therefore not easy to spot when they are lined up against the foliage of a woodland floor. To be honest, I was quite pleased with myself for managing to spot this indistinctive plant!

However once I had a closer look, there was more to see. One particular patch was very heavily infected with what appeared to be the fungus Puccinia albescens, which covered the leaves, stem and flowers of several plants. This species is a rust fungus, which is a type of fungus that usually parasitises wildflowers and other small plants. There is an incredible diversity of host plants within the 7000 species of rust fungi as most plants are only infected by a single species.

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The close-up photograph above shows the pustules of the rust fungus, which is just one part of the complex life-cycle of rust fungi. These pustules erupt at this time of year and produce uredospores which are carried on the wind to new plants of the same species to infect.

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Telia

Also present alongside these pustules are what I believe to be the telia of the same species. These telia – the dark, round spots – are produced in the autumn in most species and would have overwintered. The telia produce teliospores, which are another method the fungus uses to spread as they disperse to find more plants of the same species to infect, just as the uredospores do.

The life-cycle of rust fungi is very complex and here I have explained it only briefly – different species of rust fungi can have different life-cycles and some infect two completely unrelated species during their life-cycle. These multi-host fungi are known as heteroecious fungi and one host plant is infected by the uredospores and the other is infected by teliospores. As Puccinia albescens is not heteroecious (and is autoecious), its life-cycle can be completed on just a single host species – Moschatel – and the single host species is infected by both the uredospores and the teliospores. Some good websites to visit for more information on the life-cycle of rust fungi are:

http://www.biologydiscussion.com/fungi/life-cycle-and-the-spore-stage-of-rust-fungi-fungi/64083

http://website.nbm-mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Pucciniales.html – this one includes a lot of information, however it also contains a lot of scientific jargon and complicated vocabulary.

It’s Popping Hot

Some people find plants boring. However, they are very clever. How can a plant be clever? Through evolution, plants have developed many fascinating ways to survive and thrive.

The key to a plant’s success is largely in the seed dispersal technique. Without a way to disperse seeds, plants would not be able to colonise new suitable habitat and spread. Therefore plants have learnt to be ingenious in their methods of ensuring the future of generations to come.

Yesterday afternoon I was walking through my local farm when I heard a few pops coming from the vegetation beside the path. At first I thought they were the calls of a grasshopper or a cricket, but definitely not a species I had heard before. I stopped and waited to see if I could hear anymore. I did, and this time I thought they sounded like click beetles, but why would so many be clicking at the same time? I was puzzled by this strange sound until, accompanied by a pop, I saw a quick movement out of the corner of my eye. I looked closer to where the movement had come from but I couldn’t see anything that I thought could have made the sound, just a patch of vetch. Then I realised that the sound was coming from the vetch itself!

Vetches are plants related to peas, they have pods like peas although usually much smaller. The pods begin green, the same colour as the leaves, and then as they mature they turn darker until they are brown. Plants in the pea family often have pods that pop, which is advantageous to the plant as it is a great method of seed dispersal. This method ensures the seed is enough distance away from the parent plant to prevent overcrowding.

Before I witnessed the popping of the seed pods yesterday I had no idea how it actually worked. How did the pods pop? I have done a bit of research and what I found out was fascinating. On hot days like yesterday the seed pods dry out, aided by the dark colour of the mature pods in some species which absorb heat. During the drying process forces build up inside the pod until it reaches a point when the pod explodes. In most pods there are two lines of weakness running along the pod, and it is here where the tensions which are set up in the wall of the pod cause the pod to explode. Similar to when a pulled spring is let back, the two halves of the pod curl back at lightning speed which flicks the seeds out of the pod!

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These two pods are still green and have not dried enough to pop.

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Two seed pods which are ready to pop! They have dried in the hot weather and turned brown.

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Two freshly-popped seed pods, showing the two halves of the pod

 

Some interesting Blackbird behaviour

There has been some drama happening with our Blackbirds this year. Before exactly a month ago, we had a regular pair of Blackbirds that inhabited our garden and regularly visited the space under our feeders. We could tell this pair from the other Blackbirds as both were ringed earlier in the year. They had built a nest in the middle of March, which had 3 eggs in by the time I left on holiday to South Africa. When I returned the eggs should have been at the nestling stage, but the nest was empty.

On the 1st of May I noticed 4 male Blackbirds chasing each other around the garden pursued by a female. They disappeared out of view until a few hours later I spotted a male singing in the tallest Oak that I can see from my bedroom window, which leans over into our garden from our neighbour’s. It wasn’t ringed.

A few days later something I wasn’t expecting appeared below our feeders. A juvenile Blackbird. There was still no sign of the original pair, so this one must have been brought in by the currently dominant pair. But why only one? I think that as this is still quite early in the year, the parents might not have been able to find enough food for all 3 or 4 of their chicks, especially considering the strange weather we have been having. I will keep watching the Blackbirds to see if the ringed pair re-appear.

From what I have researched about Blackbird territories, I think that my garden must be quite a good habitat for them. The RSPB say that they are solitary birds, but “Small feeding and roosting aggregation sometimes form at good sites”. We have around six Blackbirds in our garden throughout the year and more in the winter when migrants from the mainland come in. There currently seem to be 3 pairs and therefore 3 territories in our garden, one in the front garden, one in the front half of our back garden and one at the back of our back garden. The size of these territories seems quite small for Blackbirds, so there must be good concentration of food. Inevitably, there have been squabbles from time to time.

I will continue to watch these Blackbirds. Who knows what interesting behaviour I could see next or will I locate the ringed pair?

 

 

 

 

Cell Rap!

My name is James

And I love all cells

There’re animal and plant cells

‘N’ I think they’re swell!

 

Both types have a nucleus

That stores the DNA

It also helps to make protein

And control its ev’ry way.

 

Chloroplasts are clever

And only plant cells have ‘em

They help in photosynthesis

And the plant’ll die without ‘em!

 

Starch grains are very useful

And unique to only plants

The membrane decides what’s in and out

And helps both animals ‘n’ plants

 

Cytoplasm is jelly-like

And the site of all reactions

Now let’s move on to more cell parts

My favourite plan of action!

 

All plant cells have a wall

To help keep the cell’s structure

It also seems to save the cell

From a devastating fracture

 

The vacuole is vital

‘Cos it helps to keep its shape

It also has a special sap

And resembles a tiny grape!