Arthropoda
Introduction:
Arthropods are the largest group of invertebrates, they also happen to be the largest phyla in all of the animal kingdom with over 84% of all known species of animals belonging to this group.
The arthropods include crustaceans, arachnids, mites, insects, centipedes, millipedes and horseshoe crabs- some of the most ancestral animals still surviving today.
They are characterised by their segmented bodies and jointed limbs, aiding movement so they can swim, walk and crawl all over the place. Arthropods are found in almost all habitats across the globe from the deep seas to the peaks of mountains.
One of the reasons the group is so large is due to their expansion on land. Back in the Early Silurian, they were the first animals to leave the safety of the oceans and venture onto land and take advantage of the abundant plant life resulting from the Green Revolution. Insects in particular underwent a huge diversification of species, remaining to this day one of the largest groups of animals. Learn more about our specific insect collections here.
In the museum the arthropods can be found in outer cabinets 11 to 17.
Adaptations:
Arthropods are distinguished by their jointed external skeleton composed of chitin bound to protein. Their bodies are meteorically segmented, linear repeating segments each containing organs and tissues.
The exoskeleton provides physical protection from predators and prevents the arthropod from drying out. it also provides body support- features particularly important for terrestrial arthropods especially the insects.
All arthropods have appendages on segments. These appendages can be specialised for different functions e.g.
antenna or feeding structures on the head.
Legs on the thorax for swimming/walking
Or limbs on the abdomen used for movement of for holding eggs
Segments can fuse together to form specialist structures that aid the animal- this is apparent when looking between the different arthropod groups. E.g. arachnids have only two primary body parts, while insects have three.
Many terrestrial arthropods evolved book lungs or trachea to breathe air through unique respiratory systems.
Classification:
Extant (non-extinct) arthropods are mostly classified based on the number of body regions (segments), legs, limb specialisation and if antennae are present.
Chelicerata
Aracnids: spiders, scoriopns, horseshoe crabs
Myriapoda
Millipedes and centipedes
Crustacea
Crustaceans: crabs, lobsters crayfish, isopods etc
Hexapoda
The insects: flies, ants, silverfish, bees, cockroaches, moths, beetles, butterflies etc
Explore the arthropod groups further with Onezoom
Museum Highlights:
Mantis shrimp: heavily armoured crustaceans with bright colours and spear like limbs that can impale their targets with super strong punches that can break glass.
Fiddler crab - known for the giant oversized claw of the male used for defending territory and in mating rituals. They also help preserve coastal wetlands by burrowing into the mud of the marshes which oxygenates the sediment allowing other plant and animal life to thrive.
Eurycnema versirubra, the red-winged green giant stick insect, which true to its name reach up to 27cm in length (for females, 16cm for males).
Horseshoe crab- the only living members of the order Xiphosura. These ancient creatures have been around for over 200 million years, appearing in the Mesozoic era, earning them the name 'living fossils'
Tanzanian Blue Ringleg Centipede, Scolopendra morsitans- a highly venomous centipede from Africa and Australia which hunts small insects and earthworms
Extensive pinned insect collection with insects from every major order, including some from prolific entomologists such as Arthur Doncaster
