A huge garbage pile reeking of stagnant water and decaying vegetables. Carcass of a dead animal lying next to it. The area is under siege! It’s time for nature’s disaster management squad to swing into action – the scavengers.
Scavengers are birds and animals that feed on dead (or injured) animals and plants. They clean the planet’s organic waste. The moment they get nature’s warning signal – odour – they quickly come to the rescue. They break down the organic material into smaller pieces, which are then eaten by decomposers and broken down into chemical parts. These chemical parts, including nitrogen, carbon and other nutrients, are used again by plants and animals. So, without scavengers, the world would be covered with dead plants and animals!
Here are a few of the heroes:
Cockroaches eat all kinds of materials – from paper to cloth to dead animals and plants. They have been on earth for over 340 million years, and there are about 3,500 species of them in the world. Though they are adapted to live in almost any environment, most of them live in the woods and feed on dead plants, and some live in our homes and feed on garbage.
Many bugs, like carrion beetles, dung beetles, sow bugs, pill bugs and earwigs, scavenge on dead or decaying organic matter. But they may even feed on young plants, plant roots and other parts, though the damage done is minimal. Some flies, like blowflies, are also scavengers.
Most earthworms are scavengers that feed on plant waste, like dry leaves. When they feed, they convert dead organic matter into rich humus required for the growth of healthy plants. They also ingest other small soil particles (even stones up to 1/20 of an inch), which when excreted in the form of casts provides valuable minerals and nutrients. And their burrowing activities keep the soil structure open for better aeration and drainage.
Slugs and snails
There are various types of slugs and snails, and their feeding habit differs accordingly. They are mostly scavengers thriving on fungi, rotting plants and leaves, dead animals and animal dung. Some slugs even eat worms.
Crows are scavengers that practically eat anything – starting from roadkills, insects, frogs, snakes, mice, corn, human cooked food, to even eggs and nestlings of other birds!
Vultures are scavengers that only eat carrion (the flesh of dead and rotting animals). Their excellent eyesight and keen sense of smell helps them locate rotting meat. They are generally bald, preventing the dead meat and bacteria from collecting in their feathers. Some, like the turkey vulture, urinate on their legs to cool themselves. And the acids in the urine kill the bacteria on their legs!
Then there are other scavenging birds like condors, seagulls, and storks.
Oceans have scavengers too! Crabs, lobsters, shrimps, remoras, young marine eels, sharks and many more are members of the sea cleanup squad. While crabs and lobsters wait for food scraps to float by and then grab them, sharks munch on marine animal carcass. And Remoras swim near them and other large fish, and eat their leftovers. Young marine eels eat dead fish and crustaceans.
There are some full-time scavengers and some scavenge only when there is a dearth of food.
So next time you see a so-called pest, you better think twice before laying your foot on it... because you might be killing your rescuer.
Decomposers (or saprotrophs) are organisms that decompose (decay) dead organisms, and use organic substrates to get their energy, carbon and nutrients for growth and development. When a plant or animal dies, it leaves behind nutrients and energy in the organic material. Scavengers feed on their carcasses and litter.
But they leave behind a lot of energy and nutrients in the form of unconsumed portions (indigestible litter, bones, feathers or fur) and their feaces. Decomposers complete the process by breaking down this remaining organic matter, and converting all it into carbon dioxide and nutrients like nitrogen, phosphorus, and magnesium. They re-supply nutrients to the ecosystem. The primary decomposers are bacteria and fungi.