How to make a DIY under-gravel filter for your aquarium.

My weekend project was to set up an old aquarium I came across lying around. The aquarium originally came with its own filtration system but that had stopped working.

So, I took the opportunity to build and set up an under-gravel filter for this aquarium. In an under-gravel filter, water is sucked across a bed of gravel and circulated to the top of the water column.

Bacteria colonise the gravel bed and are able to break down harmful nitrogenous and other wastes. The water also gets oxygenated as it fall at the top. I have used this kind of filtration for most of my aquariums in the past and have had a good experience with it.

Here is how I went about building it:

A hundred thousand spiderlings!

On a recent visit to Karimanoor, I came across these recently hatched spiderlings. Spiderlings are immature spiders. The female spider lays between tens to thousands of eggs and encases them in a silk covering case. The sac is usually guarded by the female until the young ones are ready to hatch. Usually the spiderlings stay inside the sac until they are ready to emerge, living off the yolk. In this video they have emerged and are resident within the web that their mother spun. They will then moult as they grow and go off to create their own web and hunt for themselves.

The Black Crazy Ant carrying large prey

Paratrechina longicornis is also called as the Black Crazy ant as they are fast and dash around erratically almost as if going crazy. They are thought to be one of the most widespread species in the world, occurring both indoors as well as outdoors. Indoors, they are equally at ease in homes and in commercial establishments, displaying remarkable ability to adapt to new habitats and out-compete other species of ants. They are now considered an invasive species and as pests.

They build their nests in places ranging from loose bark, in rotten wood, under logs or stones, among rubbish, stacked newspapers or books and under undisturbed debris inside buildings. They also feed on everything from insects to sugar and plant secretions, fruit and a range of household scraps.

The workers cooperate to lift heavy prey and other food, which is carried back to their nest. Here I have captured some footage of the workers lifting heavy material and carrying it back to their nest. 

Praying Mantis staring back at my lens

Looking out for another macro opportunity but not finding any, I sat down for a rest and out of the corner of my eye, caught some movement. Almost perfectly camouflaged against the parapet I was sitting on was this praying mantis. As I lowered my lens, it seemed curious and did a little jig looking right back at me through the lens. Check it out.

Life in the undergrowth - a grass patch

On a recent visit to Mysore, I took my mobile macro setup along. While my wife was submitting her PhD thesis, I hung around outside on the campus with lots of greenery around (and students). Sitting in a grass patch, it was amazing to observe the insect life around. I only managed to capture a fraction of the life I observed, but here is a compilation of what I managed.

Crematogaster ants and predation.

Crematogaster ants are a genus of ants found worldwide, that are characterised by a distinctive heart-shaped gaster (abdomen). Most species are arboreal. These ants are also known as acrobat ants.
These ants are also called as cocktail ants because of their habit of raising their abdomens when alarmed. They are able to raise their abdomen forward and over the thorax and head and point their abdominal tip in nearly all directions allowing them to spray venom. The venom stuns their prey. They also release a pheromone to attract other workers to capture the prey. The prey is then spread out by ants pulling the victim outstretched and carried back to the nest.

I documented several instances of Crematogaster ants with their prey and have compiled them into a video. You can watch it below.

Parthenium beetle (Zygogramma bicolorata)

The Parthenium beetle (Zygogramma bicolorata) is so called as its larvae feeds on the leaves of the highly invasive Parthenium weed.

It is of Mexican origin, but was introduced into Bangalore in 1984 to control the Parthenium hysterophorus weeds. It is now a well established species in India.

Some variation in the pattern on the wing is common.