Arthropods are animals that are members of the phylum Arthropoda. More than 80% of all of the animals in the world are arthropods. With such a large group of animals, there is quite a lot of diversity – and quite a lot of examples – but they do have some similar traits:
- Invertebrates
- An exoskeleton, or external, skeleton made of chitin and it is covered with a thick protective layer, or cuticle
- Segmented bodies
- Six legs or more which are jointed. In fact, their name comes from the Greek words for “joint” and “foot.”
Basic Categories of Arthropods
Here are some basic examples of arthropods sorted by the non-extinct subphyla:
- Chelicerata: horseshoe crabs, spiders, scorpions, sea spiders and mites
- Myriapoda: millipedes, centipedes, pauropods and symphylans (known as glasshouse symphylans or garden centipedes)
- Crustacea: brine shrimp, barnacles, lobsters, crabs, shrimp and remipedes
- Hexapoda: insects and three orders of entognatha: collembola, proturans and diplura
Reproductive methods are diverse among arthropods but most begin life as an egg. As they grow, their exoskeleton splits in the back and the arthropod slips out of it and grows another one which is bigger. This process can take from a few minutes to several hours, during which time they are vulnerable to predators.
Types of Arthropods
A large majority of arthropods belong to the three main groups:
- Insects
- Arachnids
- Crustaceans
Insects (Subphylum Hexapoda)
Since there are three-quarters of a million insect species, it’s best to just look at some of the common ones. They include:
- Ants
- Aphids
- Beetles
- Butterflies
- Cicadas
- Cockroaches
- Dragonflies
- Fleas
- Flies
- Grasshoppers
- Leaf hoppers
- Lice
- Mayflies
- Praying mantis
- Stink bugs
- Silverfishes
- Termites
- Walking sticks
All insects have six legs which are arranged in pairs. They also have two antennae and most of them have two compound eyes. Typically you will find two pairs of wings on insects, with some of them having only one pair, like flies. A few insects have no wings, like ants, fleas, and lice. Insects are the only invertebrates that can fly.
Arachnids (Subphylum Chelicerata)
The three main orders of arachnids are:
- Scorpionida (scorpions)
- Acarina (ticks and mites)
- Araneae (spiders)
There are over 100,000 species of arachnids. Common ones include:
- Black widow spider
- Brown recluse
- Chiggers
- Crab spiders
- Daddy longlegs
- Harvestmen
- Mites
- Orb weavers
- Scorpions
- Spiders
- Ticks
- Vinegaroons
- Whip tailed scorpions
- Wind scorpions
Arachnids are eight-legged arthropods with no wings or antennae. Most arachnids live on land; but, a few species can be found in fresh and salt water habitats.
Crustaceans (Subphylum Crustacea)
The number of species of crustaceans is over 40,000. Some of the common ones include:
- Barnacles
- Brine shrimp
- Crabs
- Crayfish
- Fish
- Lice
- Horseshoe shrimp
- Krill
- Lobsters
- Seed shrimp
- Shrimp
All crustaceans have ten legs or more and most of them are found living in water. The majority of aquatic crustaceans live in salt water; but, a few live in lakes and rivers. Woodlice are one of the small numbers of crustaceans who live on land.
