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Valentine’s Day is a time to show appreciation for loved ones, whether that is your partner, family, friends, or maybe your invertebrate pals in parks and gardens!

Here are five invertebrate facts that (tenuously) prove that February 14th isn’t all about us humans:

1. Worms have five hearts (so have a lot of love to give)

Well, sort of… invertebrate circulation is a bit different to that of a mammal. Instead of a heart, earthworms have five ‘aortic arches’ which are muscular structures that pump haemolymph (their equivalent to blood) through a network of vessels to transport oxygen around the earthworms’ long bodies.

2. Woodlice like hugs (sort of)

Woodlice are thigmophilic (one of my favourite words) – meaning that they respond to a touch stimulus and like to feel contact, like having a hug. Under logs, flowerpots and in cracks in wood, a woodlouse has contact on multiple sides of its body, which helps it feel safer because it makes it harder for predators to attack. The next time you are going on a bug hunt, take a look under a log, but remember to gently put it back again to keep those bugs snug.

3. Spiders can be gift givers

Some male spiders, such as the nursery web spider (Pisaura mirabilis), use food to woo the ladies. Males will catch an insect and wrap it up in silk to offer to a female. The female then judges the quality of her potential mate by the quality of the male’s gift.

The giving of presents, known as nuptial gifts1, is not uncommon in the invertebrate world - a female receiving a gift gets the benefit of additional energy to produce offspring. For the male, giving a good gift increases the chance to pass on his genes. However, it costs a lot of energy to catch or produce a gift, leading some males to cheat2 by wrapping up a ‘worthless’ gift in silk! Can you imagine receiving an empty box of chocolates on Valentine's Day? The cheek of it!

4. Mayflies like to dance

If you have ever been pond dipping, you will likely have seen several mayfly nymphs swimming around with their three ‘tails’. These youngsters live in the water for up to two years feeding on algae and plant matter before emerging as a sub-adult and then moulting and emerging as an adult with wings. Many species don’t live for long as adults (some for less than 30 minutes), and don’t feed during this time, so their aim is to find a mate and lay eggs.

Clouds of mayflies can often be seen flying and dancing together above freshwater, looking quite beautiful as they catch the light. Time and predators are against them (mayflies are important sources of food for birds, fish, and other invertebrates), so these mating swarms are an important opportunity to mate and continue the life cycle.

5. Pollinators love to receive flowers

Flowers are common gifts with the UK spending more than £20 million on blooms at Valentine’s, but why not give our pollinators some love too? Wildflower seeds or letting an area grow wild are cheaper than cut flowers!

Unfortunately, 97% of the UK’s wildflower meadows have been lost since the 1930s3. This loss of habitat is affecting many of our pollinators, and is one reasons that a third of British wild bee and hoverfly populations are in decline4. Planting for pollinators can ensure that there is nectar available throughout the year for our pollinating bees, flies, butterflies and beetles.

Common earthworm

Common shiny woodlouse

Nursery web spider

All of these invertebrates can be found in The Royal Parks and across the UK, and they should be appreciated throughout the year, not only at Valentine’s Day. So, don’t forget to show them some love too, because our world would be very different without them.


Tiger hoverfly

1Prokop P., Maxwell M., 2012, Gift carrying in the spider Pisaura mirabilis: nuptial gift contents in nature and effects on male running speed and fighting success, Animal Behaviour, volume 83, issue 6, pages 1395-1399

2Ghislandi P. et al., 2017, Silk wrapping of nuptial gifts aids cheating behaviour in male spiders, Behavioural Ecology, volume 28, issue 3, pages 744-749

3Barkham P, 2015, 97% of Britain’s wildflower meadows have gone. Here’s why it matters, The Guardian, 18 May 2015

4Powney G. et al., 2019, Widespread losses of pollinating insects in Britain, Nature Communications, volume 10, article 1018

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