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Monday, 5 October 2026

Global Animal Guide

Animals A–Z index Conservation Wildlife help

Invertebrates

The guide features 45 species in the invertebrate class. Each profile answers the most-searched questions first.

What are invertebrates?

Invertebrates are animals without a backbone — a vast group that accounts for around 97% of all animal species. It includes spiders, molluscs, crustaceans, corals, jellyfish, and worms. Lacking an internal skeleton, many rely on hard outer shells, hydrostatic pressure, or exoskeletons for support, and they live in virtually every habitat from the deep sea to the soil beneath our feet.

Common octopus on a coral reef with curling arms and textured skin

Invertebrate

Octopus

The shape-shifting genius of the sea

Female black widow hanging upside-down in a cobweb showing red hourglass on abdomen

Invertebrate

Black Widow

Venomous cobweb spider with a red hourglass

Translucent moon jellyfish drifting in deep blue ocean water

Invertebrate

Jellyfish

The ancient, brainless drifter of the seas

Tarantula on rocky desert ground with detailed hairy legs

Invertebrate

Tarantula

The large, hairy spider with a gentle reputation

Brown recluse spider showing violin marking on cephalothorax

Invertebrate

Brown Recluse Spider

The violin-marked spider of the American South

Blacklegged tick on a green leaf with legs spread

Invertebrate

Blacklegged Tick

The Lyme disease vector of eastern forests

Coconut crab climbing a palm tree trunk at night showing its large orange-brown body and powerful claws

Invertebrate

Coconut Crab

The world's largest land arthropod and tree-climbing island giant

Giant house spider with long brown legs resting on a pale surface showing its large size

Invertebrate

Giant House Spider

Britain's large but harmless funnel-weaving house spider

Red abalone with oval shell and row of respiratory pores clinging to California kelp reef

Critically Endangered

Invertebrate

Red Abalone

Critically Endangered nacre snail of Pacific kelp

Edible sea cucumber with dark mottled skin crawling across Indo-Pacific sand flat

Invertebrate

Sea Cucumber

Soft recycler of tropical reef sediments

Live sand dollar partially buried in Atlantic sand showing purple spine fringe and flower pattern

Invertebrate

Sand Dollar

Buried flower of Atlantic sand flats

Gumboot chiton on rocky tidepool with brick-red leathery mantle covering eight shell plates

Invertebrate

Gumboot Chiton

Leathery giant of Pacific tidepools

Feather star perched on reef with feathery arms extended and clawed cirri gripping substrate

Invertebrate

Feather Star

Filter-feeding crinoid that walks on cirri

Brittle star with spiny arms raised off gravel seabed in dense aggregation

Invertebrate

Brittle Star

Arm-dropping filter feeder of Atlantic gravel

Box jellyfish with transparent cube-shaped bell and long pale tentacles in tropical shallows

Invertebrate

Box Jellyfish

Cube-shaped killer of Australian shallows

Moon jellyfish pulsing with four pink horseshoe gonads visible through transparent bell

Invertebrate

Moon Jellyfish

Glass-disc drifter of harbours worldwide

Pistol shrimp with one oversized snapping claw emerging from reef burrow beside goby partner

Invertebrate

Pistol Shrimp

Cavitation snapper of reef burrows

Japanese spider crab with long spindly legs and knobby carapace on deep Pacific slope

Invertebrate

Japanese Spider Crab

Record-span scavenger of Pacific depths

Vampire squid hovering in deep water with webbed arms and red-blue photophores

Invertebrate

Vampire Squid

Detritus-eating cape of the oxygen minimum zone

Dumbo octopus hovering above abyssal mud with ear-like fins flapping beside pale body

Invertebrate

Dumbo Octopus

Fin-flapping octopus of the abyssal plain

Giant Pacific octopus with reddish skin and suckered arms flowing from rocky den

Invertebrate

Giant Pacific Octopus

Largest octopus of the North Pacific

Water bear tardigrade with eight stubby legs and barrel body viewed under microscope

Invertebrate

Water Bear

Near-indestructible moss dweller under the microscope

Velvet worm with blue-green velvety skin and stubby legs on rotting log in rainforest

Invertebrate

Velvet Worm

Slime-shooting living fossil of leaf litter

Transparent sea angel with wing-like parapodia and orange gut visible in cold polar water

Invertebrate

Sea Angel

Shell-less winged hunter of polar seas

Crown-of-thorns starfish with venomous spines draped over bleached coral on Indo-Pacific reef

Invertebrate

Crown-of-thorns Starfish

Spiny coral scourge of Indo-Pacific reefs

White sea bunny nudibranch with fuzzy texture and ear-like rhinophores resting on coral reef substrate

Invertebrate

Sea Bunny

The tiny nudibranch that went viral for looking like a miniature rabbit

Cuttlefish hovering above the seabed with a patterned mantle and wavy fins

Invertebrate

Cuttlefish

The color-changing master of camouflage

Glossy black widow spider hanging in its web showing the red hourglass marking

Invertebrate

Black Widow Spider

The glossy black spider with the red hourglass

Orange five-armed starfish resting on a rocky tidal seabed

Invertebrate

Starfish

The five-armed drifter that regrows its limbs

Blue crab with bright blue claws and a broad shell on a sandy estuary bottom

Invertebrate

Blue Crab

The swift swimming crab of Atlantic estuaries

Peacock mantis shrimp with vivid green, red, and blue body peering out of a reef burrow

Invertebrate

Peacock Mantis Shrimp

The reef brawler with the fastest punch in nature

Colorful coral colony with many tiny polyps on a sunlit tropical reef

Invertebrate

Coral

The tiny reef-building animals of tropical seas

Atlantic horseshoe crab with a domed shell and long pointed tail on a sandy beach

Invertebrate

Atlantic Horseshoe Crab

The ancient living fossil with blue blood

Close-up of a fuzzy jumping spider with large round front eyes on a leaf

Invertebrate

Jumping Spider

The big-eyed spider that pounces on its prey

Giant squid with long tentacles and huge eye in deep dark ocean water

Invertebrate

Giant Squid

The elusive deep-sea giant with enormous eyes

Chambered nautilus with a spiral striped shell and many small tentacles in dark water

Invertebrate

Chambered Nautilus

The living-fossil cephalopod in a spiral shell

Reddish-brown centipede with long antennae and many legs on damp leaf litter

Invertebrate

Centipede

The fast, venomous predator with many legs

Dark blue-green American lobster with large front claws on a rocky seabed

Invertebrate

American Lobster

The long-lived clawed crustacean of cold seas

Dark cylindrical millipede curled on the forest floor with many short legs

Invertebrate

Millipede

The slow, many-legged recycler of the forest floor

Large glossy black emperor scorpion with raised tail and big pincers

Invertebrate

Emperor Scorpion

The large, glowing arachnid with a stinging tail

Hermit crab peeking out of a spiral snail shell on wet sand

Invertebrate

Hermit Crab

The crustacean that wears borrowed shells

Brown-shelled garden snail gliding across a green leaf

Invertebrate

Garden Snail

The slow, shell-carrying garden mollusk

Dark purple spiny sea urchin clinging to a rocky reef surface

Invertebrate

Sea Urchin

The spiny ball that grazes the seabed

Reddish-brown earthworm on dark moist soil

Invertebrate

Earthworm

The soil engineer that enriches the earth

Giant clam on a coral reef with brightly colored, wavy mantle tissue

Invertebrate

Giant Clam

The reef-dwelling giant of the mollusks

Frequently asked questions

What are invertebrates?

Invertebrates are animals without a backbone — a vast group that accounts for around 97% of all animal species. It includes spiders, molluscs, crustaceans, corals, jellyfish, and worms. Lacking an internal skeleton, many rely on hard outer shells, hydrostatic pressure, or exoskeletons for support, and they live in virtually every habitat from the deep sea to the soil beneath our feet.

How many invertebrates are in the Global Animal Guide?

The Global Animal Guide currently features 45 invertebrates with full, answer-first profiles covering diet, habitat, size, and conservation status.