Kingdom in the canopy (I): Biodiversity in Bromeliads

During the University of Manchester's Tropical Biology field course in Payamino, Ecuador, I was studying the biodiversity within bromeliads. Not only is the arboreal cake that is the neotropical canopy layered with tiers of different plants, but many of these are inhabited by a variety of animals. 

Bromeliads make particularly good environments for critters to colonise, as the spiralled, rosette arrangement of their leaves (see Image 1) allows rainwater and debris to accumulate between the gaps. The equivalent of tiny ponds may appear, sufficient to act as nurseries for tadpoles; or soil may gather, enough to grow ferns and vines. A bromeliad is like a hanging garden basket – only better. Maybe a hanging zoological garden.

Image 1 - Bromeliads in flower. Both the leaves and the flowers of bromeliads serve as homes for other life forms. The first two pictures, from the left, are taken in the Botanical Gardens in Quito. The right-most picture is taken in Payamino and is one of the types of bromeliad I've been collecting. © Xaali O'Reilly, 2012

The best way to study what's living inside bromeliads precisely, is to take them down, take them apart, and take out the critters creeping about and the epiphylls clinging to the leaves. This may strike you as unnecessarily destructive. However, I can safely say that trying to count and classify all the lifeforms hiding between what are often sharp-edged, serrated bromeliad leaves, while standing on tip-toes, on somebody else's shoulders, or dangling from semi-static rope is near impossible. Besides, the rainforest is so heavily adorned with bromeliads, that the sample size for a university field course biodiversity survey could hardly dent population sizes. Additionally, many of the collected individuals had already flowered, and therefore not long for this world.

Image 2 - Aroids clumped in a mass of other epiphytes, about 20m up.
© Xaali O'Reilly, 2012

Enough excuses.

One of my previous posts (Who's Who Up a Tree - Epiphyte IDing) pointed out some basic differences between some of the major groups of epiphytes in the South American rainforest, although – due to my ignorance – I left out one of the most prominent families, Araceae, which I'll have to read-up on before I can talk about (Image 2).

For now I thought I'd share some of the animal residents of my bromeliads.

Something there were a lot of in most of the bromeliads I collected, were ants. Different types, too – sometimes different morphospecies of ant within one bromeliad. A morphospecies is a classification based on the morphology or physique of a living organism. This doesn't always strictly correspond to a biological species, because many species have different individuals which look very different from each other (think worker ants and their queen, for example; or a male and a female peacock!).

Coackroaches were another common sight. Scurrying about the place. There are many different species of cockroach, so it wasn't your common house coackroach dwelling in the epiphytes.

Pill bugs or "bicho bolas", as I've grown up calling them (Spanish for "ball bugs"), were an amusing thing to come across. It brought me back to when I first moved to Spain – in school, during break time, we'd play with the poor curled-up isopods as if they were marbles.

Earthworms, katydids, true bugs and cicadas, earwigs, millipedes and some nasty centipedes, beetles and their larvae, as well as fly, dragonfly, and butterfly, larvae, had all made homes in the bromeliads. However, any of you who know me will not be surprised to hear that I was particularly excited about the arachnids I came across. These included a tick, a couple of harvestmen or Opiliones (Image 3), an adorable pseudoscorpion (sort of like a tiny scorpion without a sting…), and a host of spiders.

Image 3 - A harvestman (Opiliones). © Xaali O'Reilly, 2012

As if this weren't enough for me, hiding between the leaves of a bromeliad which had been hanging off a tree at 13 metres, was beautiful example from my favourite arachnid family: a huge hairy tarantula clinging an egg-sack (Image 4). I named her Orna, after my (arachnophobic) mother, who shares with the spider in having a large family. As far as I can tell, all New World arboreal tarantulas belong to the subfamily Aviculariinae. And given the size of the scopulate pads (a sort of hairy toe pad that all tarantulas have but tend to be larger on arboreal species) that fine lady possessed, I'd like to think that she was indeed an aviculariine. Tempted as I was to keep her and study how she cared for her egg-sack and how her young hatched, she was freed onto a branch. Hopefully she found a nice new bromeliad to her liking.

Image 4 - Orna the tarantula (Theraphosidae; Aviculariinae) with her egg-sack. © Xaali O'Reilly, 2012

I'm not sure whether I was more excited about Orna the tarantula or what I found in another bromeliad the very next day – a little poison arrow frog! (Image 5). This guy was a Dendrobates imitator, so named as they resemble very closely another species of frog in their area. Not only that, but throughout the imitator's range the species manifests different colourations, in accordance with the different patterns of the species it imitates. 

Image 5 - Dendrobates (Ranitomeya) imitator, a poison dart or arrow frog. © Xaali O'Reilly, 2012

Since the Manchester groups left, there hasn't been anybody around qualified to act as ground crew, thus I had not been able to climb trees while drawing up a lesson plan to teach some of the local guides the basics of acting as ground crew. Then I broke my wrist and it's still on the mend, so that has further delayed any bromeliad collecting. However, I do intend to continue investigating the biodiversity within these beautiful examples of epiphytic architecture, so I'm sure they'll be more bromeliad-related posts here in the future!