Anataomy of a Worm

Now that you have your worms home and in their worm farm or in your garden the team here at Worm Affair want to help you take care of your worms so they can thrive and provide you with years of service and enjoyment.

Lets start with a brief look at the anatomy of a worm, this will help you to better understand what a worm needs to be happy and productive. A common question that is asked is “what is the difference between an Earthworm and a Compost Worm?” put simply the main difference is in the environment they live in, compost worms live and work close to the surface, normally in the top 150mm of soil though they will burrow deeper in ideal conditions, they feed on decaying organic matter and prefer a wetter environment while earthworms are deeper burrowing worms who will come to the surface to collect a piece of organic matter then carry it down to be consumed, these worms are normally larger worms but slower growing. Compost worms are smaller, growing to about 50 – 200mm long depending on species.

Circulatory system and Movement

Worms have 5 pairs of hearts, these are crucial for not only the circulation of blood but also their movement, worms are a combination of a hydraulic ram and jack, they are able to exert huge amounts of force with the help of these hearts all while being a fluid motion of contraction and expansion. Along the body of a worm is an array of tiny hairs call “Satae”, these hairs are what allow the worm to grip the surrounding soil and exert the forward force to move through the soil, they are connected to muscles which allow them to be extended and withdrawn in time with the body’s movements.

Respiratory System

A worm does not have lungs as we do, instead as the blood travels along the worms’ body it passes through the skins capillaries where the waste gasses are expelled and oxygen from the surrounding soil is absorbed and circulated through the worms organs with the help of those hearts. For this process to occur the worms’ skin must be moist, this is why it is important that the bedding in your worm farm is always moist but not too wet. It is also why you can see worms coming to the surface after days of heavy rain. The ground becomes soaked with water and the oxygen being lighter floats out of the soil forcing the worms to the surface for oxygen, it is just unfortunate that the worms are very vulnerable to predators and the sun and often meet their fate.

Digestive system

This is where the magic happens, Worms have a digestive system similar to a bird. Once food in ingested it passes into a “gizzard” where the food is ground down to a fine paste and a secretion of calcium carbonate is added to aid the break down of the material, the ground food then moves on to the intestine where millions of bacteria and a variety of enzymes continue to work on the food further breaking it down and releasing the nutrients for the worm to absorb. Once the now digested food leaves the intestines it is excreted through the anus where it becomes microbe rich castings. Not only is the casting full of plant available nutrients it contains a very large number of those enzymes and bacteria from the worm’s intestines which continue to work on the surrounding soil. So even after the worm as moved on, the casting continues to convert the soil surrounding the cast into a more nutrient rich soil ready for plant roots to absorb. This is why the humble worm is a gardener’s best friend.


Worms are hermaphrodites, this means they have both male and female genitalia, for a pair of worms to mate they must be of similar size otherwise mating won’t be successful. Reds and Tiger worms reach sexual maturity at around 45- 90 days old while Nightcrawlers and Blues take a bit longer. All compost worms are egg layers and after a successful mating both worms will continue on their way and deposit eggs (also known as capsules or cocoons) as they travel. The eggs take between 14 days and 5 weeks to hatch depending on conditions, though they are able to lie dormant in the soil for years until conditions are right for hatching, Ideally a soil temperature of 18 – 25 degrees C and nicely moist.

Eggs can contain anywhere between 1 and 22 young but the average hatching rate is 4 worms per egg. In ideal conditions reds can reproduce 106 times per year and tigers around 50.

An interesting fact about Blues is that they don’t need a partner to reproduce, while they will still mate with another blue it is not necessary, they can use a process called Parthenogenetic Reproduction, in short it means that they can fertilize their own eggs. This makes them prolific breeders in the right conditions.