Invertebrates are animals without a backbone. It is estimated that invertebrates make up between 95 – 97% of all life on Earth. Scientists put this number anywhere between the 1.25 million species already described, to up to 30 million or more.
Invertebrates can be found on the land, sea, and air. They range from the microscopic rotifers, which can measure no larger than 0.5mm, to the gargantuan colossal squid, found in the ocean deep and measuring up to 14 meters in length.
But what about Costa Rica and what kind of invertebrates are found there?
Costa Rica is home to over 400,000 invertebrates, with many more still waiting to be discovered. Invertebrates found in Costa Rica include insects, such as butterflies and moths (Lepidoptera), beetles (Coleoptera), and ants, wasps, and bees (Hymenoptera). Other invertebrate species include molluscs, crustaceans, and arachnids.
Invertebrates are everywhere in Costa Rica! I was fortunate enough to carry out research on sea turtles, as well as work in a wildlife rehabilitation center, and the most common animals I witnessed were invertebrates. Even on the shoreline, invertebrates still dominated the landscape.
Invertebrates often get a bad reputation. Some bite, some spread diseases, and some destroy crops.
But, invertebrates, despite their flaws, are incredibly beneficial, not only to the overall health of an ecosystem but also to our own health. They can be used as a food source, control of harmful pests, and help decomposition. The list goes on.
This article will examine some of the invertebrates found in Costa Rica, from insects to molluscs, and everything in between.
Why Are There So Many Invertebrates?
Invertebrates are adaptable. Simple as that.
They are capable of reproducing quickly, they have an incredibly varied diet, can survive in challenging environments, and have means of locomotion that enables them to escape predators or colonise new areas.
Let’s break this down quickly.
Firstly, reproduction. Invertebrates can produce hundreds to thousands, sometimes millions, of eggs at a time. Oceanic invertebrates, such as sponges, release masses of eggs and sperms directly into the water column.
Some insects, such as ants and bees, do not require males – females can produce infertile workers, a clone of themselves. Other invertebrates, such as octopuses, are devoted parents, nurturing and cleaning eggs as they develop.
Invertebrates also eat a wide range of food types – from plant to animal matter. Some are scavengers, stripping meat right off a carcass. Others are parasitic, feeding off a living host. Some live off wood, others can only survive on the back of a sloth. The variation in food types has resulted in an explosion of invertebrate diversity.
Many invertebrates, more specifically insects, have wings. Most wings enable flight, allowing invertebrates to escape predators and continue to reproduce. Wings also allow insects to migrate huge distances, to find food, water, or shelter.
Insects Of Costa Rica
Narrowing down just 5 insects in all of Costa Rica is harder than it sounds. Below is just a selection of some of my favourites that I’ve encountered in various places around Costa Rica. Species, such as the glasswing butterfly, bullet ant, and rhinoceros beetle, did not make the list, but definitely got an honourable mention!
1. Blue Morpho
With wings of electric blue, the blue morpho lights up the dark jungle understory.
One of the largest butterfly species in the world, with a wingspan of up to 8 inches, the blue morpho can be found throughout tropical jungles of lowland Costa Rica.
But despite the vividness of their wings, they’re a fraud. The wings aren’t actually blue!
Rather, microscopic scales reflect and refract light. The result is a deception of brilliant blue.
The underside of the morpho wing, however, is a dull brown – the perfect coloration to blend in to the forest floor when resting. But, if camouflage fails, the morpho also has large eye spots on its wings to scare off potential predators, such as birds and larger insects.
2. Guanacaste Stick Insect
A master of disguise, the Guanacaste stick insect truly does live up to its name. In a nutshell, it looks the same as a stick. Their size, texture, colouration and behaviour, all mimics typical Costa Rican shrubbery.
Found in the drier Northern province of Guanacaste, this species of stick insect can go undetected – if it remains motionless. It blends in perfectly with the surrounding dry vegetation, and as a result, left mostly alone by predators.
The only times I have spotted these guys in the wild is when they have been on the move – perhaps looking for some fresh vegetation to consume. Even when they walk, they walk with a sense of disguise. As if a gust of wind is blowing through the foliage, the stick insect walks with staggered, jarring steps. A very clever evolutionary trick.
3. Leafcutter Ants
Ants, really? As one of my favourite animals of Costa Rica?
I spent about a week, albeit a very intensive week, studying these eusocial insects in the moist cloud forests of Monteverde. I could write an entire article just on leafcutters! I won’t. But I could…
At first, the prospect of studying ants didn’t excite me. I’ll be the first to admit it. Afterall, I had come to Costa Rica to study the cool megafauna! But, with a bit of time, I started to understand just how cool leafcutter ants are.
Firstly, they are a social species. Within a colony, which can have hundreds of thousands of individuals, specific “castes” can be found. These castes are divided by their body size and job role – from workers, to soldiers, to guards.
Secondly, they are exceptional farmers and cultivators. In the jungles of Costa Rica, long trails of leaf cutters can be found stretching along the forest floor. They are after one thing: leaves! Using their powerful mandibles (jaws), worker ants cut small pieces of leaves and transport them back to the nest.
However, they don’t eat the leaves. Rather, leafcutters chew pieces up, mixing the leaves with their saliva, allowing fungus to grow. When the fungus has matured, the ants harvest and eat it!
Lastly, they are expert communicators. Like other social insects, such as bees, ants communicate through scents called pheromones. Ants can detect pheromones through their antennae, and learn a message – whether it’s the location of a food source, to incoming danger.
Katydids, also referred to as bush crickets, are a species of cricket-like insect.
But, and I know you’re not supposed to have favourites, katydids are so much cooler than your average cricket.
There could be many thousands of katydids found in Costa Rica, however, one steals the limelight. The round headed katydid.
Found across the Americas, the round headed katydid is yet another master of camouflage. They are capable of mimicking leaves! Their entire body looks like a leaf, complete with veins and leaf-like textures. Some individuals even go as far as developing marks and blemishes on their wings to resemble decaying leaves.
Katydids also have a large needle-like appendage at the rear of their body. Fear not, however, for this appendage is not out to get you. Instead, it is an egg laying organ known as an ovipositor. Only females have ovipositors.
What does the stuff of nightmares look like?
Would it be a large insect with large clasping pincers? Would it be a winged beast with long, searching antennae?
Well, the dobsonfly may fit the brief.
Looking as if it has somehow escaped the nightmare world, the dobsonfly reaches lengths of up to 14 cm and has short, stubbly legs which adds to the creepiness of them. Males possess a pair of large pincers, sometimes as big as half the size of their body length!
Fortunately, these curved pincers cannot inflict a painful bite on humans. Instead, they are reserved for self-defence and territorial displays.
Females, on the other hand, had short and powerful mandibles which, if provoked, can break human skin and draw blood.
Like dragonflies, dobsonflies can be found near water sources such as rivers and lakes. Their larvae, often referred to as toe-biters, are insatiable predators, feeding off anything it can catch within its aquatic home.
Arachnids of Costa Rica
Arachnophobes, skip to the next section. But, if you’re feeling brave, read on.
While often used interchangeably, insects and arachnids are not the same. In fact, there are quite a few differences between the two animal groups. Firstly, insects have 6 eyes, whilst arachnids have 8. Insects also possess wings and antennae (mostly), whereas arachnids do not.
Costa Rica is home to approximately 2,000 different species of spiders. Fortunately, just a handful are toxic to humans. But spiders aren’t the only arachnids in Costa Rica. Scorpions, mites, pseudoscorpions and harvestmen are all non-spider arachnids that can be found across Costa Rica.
1. Striped-Knee Tarantula
Starting off the list with one of the most iconic, and feared, spiders in Costa Rica. The striped-knee tarantula.
And whilst this species of spider does have venom, the fear is unjustified. Non-lethal to humans, tarantula venom is used to paralyse prey species such as other invertebrates and small vertebrates. To us, a bite from a tarantula would be like getting stung by a bee.
However, that’s not to say the tarantula is completely off the hook. If threatened, the striped-knee tarantula can eject small hairs, or setae, from their abdomens, directing them into the eyes of a potential attacker.
Known as urticating hairs, these small hairs have barbs that are capable of becoming lodged within mammalian skin, causing severe irritation. But, if you leave them alone, they will leave you alone.
This species of tarantula is relatively common in Guanacaste, the Northwestern province of Costa Rica, where their burrows can be found in the ground and hard muddy banks. They do not build webs, and either hunt prey by chasing after it or waiting in ambush. They can detect their prey by vibration.
2. Golden Silk Orb Spider
Even to this day, this one still gives me the heebie-jeebies. It shouldn’t – as spiders provide key ecosystem services, such as pest removal (ultimately decreasing the prevalence of disease-carrying flies) – but it does.
The golden silk orb spider is a large species of orb weaving spider native to Central America. With their distinct feathery orange and black striped legs, females can grow to lengths of up to 4 inches. males, on the other hand, are a fraction of this size, and can be seen on the outskirts of the female’s web.
Being a large species of spiders, their webs are equally as large – sometimes stretching multiple meters across vegetation. But this isn’t any old web, this is a gold-plated web.
Okay, okay, maybe not quite gold as we know it. However, the silk the golden orb spider produces is full of carotenoids and quinones, giving it a distinct golden hue. This golden web acts as a dual function – luring insects into the sticky web and aiding in camouflage, depending on the angle.
The silk of the golden orb spider is also incredibly strong – up to 8 times as strong as steel. This allows the spider to catch larger prey species without them damaging the web.
This arachnid, whilst looking scary, is relatively harmless to humans. I’ve walked into many golden webs, silk tangled in my hair and spiders on my back. Yes, I may have let out a small squeal or two, but still to this day, I have never received a spider bite.
3. Tailless Whip Scorpion
If you thought the dobsonfly was the stuff of nightmares, you obviously haven’t heard of the whip scorpions.
Razor-sharp pincers, pedipalps, used for grasping prey. A flattened body to fit in the smallest of cracks and crevices. Eight small, beady eyes. Creepy.
However, for any Harry Potter enthusiasts out there, the tailless whip scorpion may seem familiar. Rising to fame in the 2005 Harry Potter and the Goblet of Fire film, tailless whip scorpions have become popular pets.
Neither scorpions, nor spiders, whip scorpi0ns belong to their own order; Amblypgi.
Unlike their appearance, whip scorpions are not aggressive and are completely harmless towards humans. It just goes to show, you can’t judge a book by its cover.
In Costa Rica, they are nocturnal hunters. They can be found in the house, but do not be alarmed. In fact, they should be welcomed. Tailless whip scorpions actively prey on pests such as cockroaches.
4. Bark Scorpion
You can understand why people don’t like arachnids. They’re scary looking.
Unlike insects, such as butterflies and moths, most arachnids aren’t ornately decorated in vibrant colours. They don’t peacefully flutter on past, slurping up a tasty nectar treat as they pass.
Instead, they’re armed with weaponry and black, beady little eyes.
And the bark scorpion is a prime example of this. Often found lurking under decaying logs or the forest understory, but not uncommon within homes, the bark scorpion is armed with not just one, but two deadly weapons.
The first weapon is a pair of powerful pincers, or pedipalps. These are covered in small hairs that help detect vibrations given off by prey species (a scorpion’s eyesight is terrible). Once a prey species, mostly insects, has been detected, the bark scorpion will grab it using their pincers. However, their pincers aren’t very strong.
This is where their second weapon comes into play.
Whilst immobilised within the clutches of their pincers, the scorpion then uses its stinger to inject their victim prey with a cocktail of venom, causing paralysis.
Although generally fairly timid, scorpions will also use their stingers in times of self-defence – say, an incoming foot in a shoe…
Yes, I am all too familiar with this situation. Working in the tropics, many species of invertebrates seek out warm, moist and dark places. Oftentimes, places that fill the brief are shoes! And, although the sting of a bark scorpion is comparable to a bee sting, it is always recommended to shake out shoes prior to wearing them. Rookie error.
5. Lone Star Tick
Yup. I hate to break it to you, but ticks are arachnids and can be found across Costa Rica.
The tick slices open the skin and inserts a barbed feeding tube, securing the tick in place. The saliva from ticks, which can contain pathogens, can often seep into the bloodstream causing sickness. The tick can remain in place for several days, until it eventually falls off to complete its next life stage.
Whilst in the Costa Rican jungles, I came out covered head to toe in ticks. Some were the size of a pinhead, barely visible with the naked eye. Others, however, had gorged themselves on my blood for a while and were the size of a thumbnail.
Granted, humans are often accidental hosts of ticks. Nonetheless, ticks spread diseases and can cause paralysis or ampholytic shock. Fortunately for me, the ticks found in Costa Rica do not spread Lyme disease – a nasty infection that is prevalent in Europe and North America.
Other Invertebrates Of Costa Rica
Invertebrates are not just restricted to the land. Some species of invertebrates can be found in the water. Cephalopods, a class of molluscs including squids and octopuses, are one such group of animals. Aquatic invertebrates also include cnidarians, such as jellyfish and sea anemones, as well as echinoderms, such as starfish and brittle stars.
Some invertebrates lack legs altogether and move incredibly slow. These are another type of mollusc known as gastropods and include species such as snails and slugs. They have one muscular foot which they move around on, and can be found on both land and sea.
1. Common Octopus
Octopi or octopuses?
Whatever the answer (although I believe octopuses is more accepted), the common octopus is a marine mollusc belonging to the cephalopod class.
The common octopus has a worldwide distribution. However, it can readily be seen throughout the rocky coastal reefs of Guanacaste. Here, they can be seen hiding away in rock crevices, waiting for nightfall, when they can begin to hunt on other invertebrates, such as crabs.
But how does an animal, seemingly soft and squishy, hunt hard-bodied prey?
The answer lies within. Found on the underside of the octopus, located in the central region of the base of the arms, a beak hides away. Resembling the beak of a parrot, an octopus beak is used to kill and dismember prey species.
If a murderous beak isn’t enough, the common octopus also contains venom. However, this is novel research, and how the octopus uses its venom remains a mystery.
But there’s more. The common octopus has three hearts! One heart is the main heart, sending oxygenated blood around the body, whilst the other two hearts pump deoxygenated blood over the gills to oxygenate it.
All very confusing for an animal with no backbone.
2. Tikaconus costarricanus
I don’t usually include the Latin names of animals in these articles because, well, no one really cares (unless you’re a scientist). However, I made an exception with this entry.
Otherwise known as the Costa Rican land snail, Tikaconus costarricanus gets its name from the slang term for Costa Ricans: “ticos”.
It is a poorly understood species, simply because of its small size and ginormous habitat. It can be found in the vast cloud forests around Rio Macho.
But this is one unusual species of snail. Documented in a recent scientific discovery, researchers studied a peculiar behaviour the snail deploys to conserve water – it hangs like a bat!
It is thought that by hanging, the snail can wrap its mantle (muscle connecting the snail body to the shell) around itself, locking in vital moisture to avoid dehydration. It could also prevent predators from detecting it.
Also known as sea slugs, nudibranchs are a group of marine gastropod species. Like terrestrial gastropods, such as slugs, they move around on a single muscle referred to as a foot. Unlike any mammalian foot (or bird, reptile or amphibian foot for that matter), sea slugs live a trail of slime on the substrate they live on.
There are over 3,000 known species of nudibranchs, with many different species found in Costa Rica. One of the easiest ways to spot nudibranchs is by hitting up the tidepools at night! But be warned, they can be small and easily missed.
Unlike other species of shelled gastropods, such as snails, sea slugs lack shells in their adult form (only larvae have shells). But, this doesn’t mean they are entirely defenceless.
Some species of nudibranchs specialise on feeding off stinging cnidarians, such as the Portuguese man’o war. The stinging cells, or nematocysts, of the man’o war can be stored in external hair-like structures of the nudibranch and can be used as a defence mechanism against potential predators.
Other species of nudibranchs can synthesize their own toxins, or obtain toxins from other food sources.
Like most gastropod species, nudibranchs use a toothed structure, known as a radula, to scape off food. However, nudibranchs lead a carnivorous lifestyle. They use digestive enzymes on their prey, such as sponges, anemones and hydroids, to help them feed.
4. Galapagos Blue Seastar
Despite its name, the Galapagos blue sea star can be found, yet again, in the Pacific coastline of Guanacaste. One of my favourite places to see these invertebrates in the wild is swimming in the deep tide pools of Playa Samara.
Seastars belong to the phylum Echinoderm, and are related to species such as sea urchins, brittle stars and sand dollars.
The blue seastar typically has 5 arms, extending from a central disk. Each arm is covered in tube feet, or podia, which are used as a form of locomotion. The tube feet have small suckers, which can be used to grab prey or adhere to an oceanic substrate – either rocky reefs or the ocean floor.
At the end of each arm, simple eyes can be found. A seastar is an animal with more than two eyes – it will have as many eyes as it does arms. The imagery that a seastar is able to produce is rudimentary, no more than 200 pixels. However, it is thought that they can see well enough to navigate.
The blue seastar has a secret superpower. It can regenerate its own limbs and is a super speedy healer. This comes in handy, especially as they are on the menu for quite a few other marine species. A sea star is able to grow an entire new body, from just one arm and part of the central disk.
5. Portuguese Man’O War
Last, but certainly not least, is the infamous Portuguese man’o war.
Commonly mistaken as a species of jellyfish, the Portuguese man’o war most certainly isn’t a jellyfish. Although, it does belong to the same phylum: cnidaria.
Unlike jellyfish, which are single organisms, the Portuguese man’o war is a colonial organism, composing of many multicellular units, called zooids, that differ in morphology and function.
For example, some zooids of a Portuguese man’o war are responsible for floating. Other zooids are responsible for capturing prey. Each colony of organisms works together as one single organism.
The Portuguese man’o war is one of the most recognisable cnidarian species of the tropics. Above the water, a balloon-like air sac rises. Colour varies, but a blue-violet colouration is the most common variation.
Underwater, however, is where the danger lurks. Long tentacles, some measuring as long as 30 meters, trail in the water column. Each tentacle is packed with thousands of stinging cells, or nematocysts – you know, the exact things some sea slugs like to gorge on.
Nematocysts are packed like a harpoon, waiting to be triggered on the slightest of touch. Upon impact, venom is pumped into an unfortunate victim, causing paralysis and death.
Now, I’ve been on the receiving end of one of these stings whilst swimming off the coast of the Osa Peninsula, in the Puntarenas province of Costa Rica. At the time, I thought a sting from a Portuguese man’o war meant certain death (I’ve been known to over-react at time). But, whilst the sting is far from pleasant, it is very rarely fatal in humans.
Invertebrates are everywhere.
They can be found on the land. In the sea. And up in the air.
Their adaptability has meant that they have colonoised, and thrived, in areas where other species cannot.
In Costa Rica, invertebrates make up up to 97% of all recoreded species – from the ocean floor to the rainforest canopy. Invertebrates come in a range of body shapes and sizes, and have a range of adpatations that allows them to successfully exploit a given niche.
Although annoying to some, invertebrates are incredibly beneficial organisms and have helped shape the evolution of life on Earth as we know it today.