Aegirocassis was a giant suspension-feeding radiodont that swam through seas covering what is now Morocco during the Early Ordovician. It was an ancient relative of arthropods, not a shrimp, crab, or lobster. At more than 2 metres long, it was among the largest animals of its time, yet its comb-like frontal appendages probably gathered plankton and other tiny food from the water.

Ammonites were extinct shelled sea animals related to modern squids, octopuses, and nautiluses. They lived in ancient oceans for millions of years and are famous for their beautiful spiral shells. Ammonites disappeared at the end of the Cretaceous Period, about 66 million years ago.

Anomalocaris was a strange ocean predator from the Cambrian Period. It was not a dinosaur, fish, or reptile, but an early arthropod relative with large eyes, swimming side flaps, two grasping front appendages, and a round mouth. It was one of the biggest predators of its time.

Ants are tiny social insects that live in colonies. They build nests, follow scent trails, care for young, collect food, protect their homes, and work together in some of the busiest little teams in nature.

Atlas moths are giant silk moths from Asian forests. They are famous for huge patterned wings, snake-like wing tips, fluffy bodies, and a short adult life focused mostly on finding a mate and laying eggs.

Aysheaia was a small soft-bodied lobopodian that walked across the Cambrian seafloor about 505 million years ago. Its worm-like body carried ten pairs of short unjointed legs, many with curved claws, while finger-like structures surrounded the mouth. Aysheaia resembled modern velvet worms, but it belonged to an extinct early panarthropod branch and was not simply a living velvet worm copied into stone.

Barnacles are ocean crustaceans that spend adult life attached to rocks, shells, boats, piers, whales, or other surfaces. They may look like tiny shells or bumps, but they are relatives of crabs, shrimp, and lobsters.

Bees are a diverse group of winged insects called Anthophila within the wasp superfamily Apoidea. More than 20,000 species have been described, ranging from tiny solitary desert bees to large social bumblebees. Most bees gather pollen and nectar for their young and move pollen between flowers, making them among the world's most important pollinators. Honey bees are famous, but they represent only a small corner of bee diversity.

Beetles are insects in the order Coleoptera, the largest described order of animals. Scientists have named roughly 400,000 species, from microscopic featherwing beetles to giant longhorns, scarabs, weevils, ladybirds, fireflies, and diving beetles. Their defining feature is a hardened front pair of wings called elytra, which closes over and protects the delicate flight wings and abdomen.

Blue-ringed octopuses are small ocean octopuses with bright blue warning rings. They may look beautiful, but they are extremely venomous, so people should never touch them and should admire them only from a safe distance.

This page focuses on jumping bristletails, the small wingless insects in the order Archaeognatha. They are not silverfish, even though both groups have tapered bodies and three rear filaments. Bristletails hide beneath bark, stones, leaf litter, or in rock crevices and can spring away when disturbed by snapping the abdomen against the ground.

Brittle stars are ocean invertebrates related to sea stars. They usually have a small central disk and five long flexible arms that can wriggle, crawl, break off, and regrow if needed.

Bumblebees are fuzzy bees that help pollinate flowers. Many bumblebees live in small colonies with a queen, female workers, and male drones, often nesting underground or in hidden grassy places.

Butterflies are colorful insects with delicate wings, antennae, six legs, and amazing life cycles. They begin as eggs, become caterpillars, change inside a chrysalis, and finally emerge as adult butterflies.

Cameroceras was a straight-shelled cephalopod that lived mainly in warm Ordovician seas. It was a mollusc related to modern octopuses, squid, cuttlefish, and nautiluses, not a fish or dinosaur. Its cone-shaped shell was divided into chambers and contained an unusually large siphuncle that helped control buoyancy. Some shells exceeded 2 metres, but famous claims of 9-metre Cameroceras are not securely supported.

Canadaspis was a small bivalved arthropod that lived near the Cambrian seafloor about 505 million years ago. Two shell-like valves covered much of its front body, while jointed limbs underneath helped it walk, swim, breathe, and move food toward its mouth. Modern research places it among early mandibulates, the broad arthropod branch that later includes crustaceans, insects, and myriapods.

Carpenter ants are ants in the large genus Camponotus. They occur in many parts of the world and include species of different colours, sizes, habitats, and behaviours. They are famous for excavating smooth nest galleries inside dead, damp, or damaged wood, but they do not digest the wood like termites. Instead, workers carry the wood fragments away while the colony feeds on insects, sweet honeydew, plant liquids, and other available foods.

Carpenter bees are sturdy bees named for the way many species tunnel into wood to make nests. They are important pollinators, and many look like bumblebees but often have shinier, less hairy abdomens.

A caterpillar is the larval stage of a butterfly or moth, an insect in the order Lepidoptera. Caterpillars hatch from eggs, spend much of their time eating and growing, shed their skins through a series of stages called instars, and eventually become pupae. Inside the pupal stage, the body is reorganised into an adult butterfly or moth. Caterpillars vary enormously in colour, size, diet, habitat, hairiness, camouflage, and defence, so this page describes the group without pretending every species follows one exact design.

Centipedes are fast many-legged arthropods that hunt small animals in moist hidden places. They have one pair of legs on each body segment and special venom claws, so wild centipedes should be watched from a safe distance and never handled.

Cicadas are noisy insects famous for their loud summer songs. Many live quietly underground as nymphs for years, then climb up trees, shed their old skins, grow wings, sing, mate, and begin the next cicada generation.

Clam is a broad everyday name for many bivalve mollusks with soft bodies protected by two hinged shells. Clams live in oceans, estuaries, rivers, and lakes, from sandy beaches and mudflats to deep water. Many burrow with a muscular foot and use siphons to move water, while their gills collect oxygen and tiny food particles. Because clam is not one formal scientific group, shell shape, size, diet, lifespan, movement, and reproduction vary enormously.

Cockroaches are flat-bodied insects with long antennae, fast legs, and a very old family history. Most cockroaches live outdoors in warm habitats, while only a few species are famous household pests.

Coconut crabs are huge land crabs from tropical islands in the Indian and Pacific oceans. They are also called robber crabs or palm thieves and are famous for strong claws, climbing skills, and cracking open coconuts.

The colossal squid, Mesonychoteuthis hamiltoni, is a massive deep-sea cephalopod found only in the Southern Ocean around Antarctica. It is shorter than the longest giant squid but has a broader, heavier body and is the heaviest known invertebrate. Adults live in freezing water at depths of roughly 1,000 metres or more, where direct observation is extraordinarily difficult. Much of what scientists know comes from rare specimens and beaks recovered from sperm-whale stomachs.

Comb jellies are soft, transparent ocean animals in the phylum Ctenophora. They are not jellyfish, even though both groups have watery bodies and drift through the sea. Most comb jellies swim by beating eight rows of fused cilia called comb plates. These moving rows scatter light into rainbow colors, while many species can also produce a separate blue-green glow through bioluminescence. Body shape, tentacles, depth, diet, and reproduction vary widely across the group.

Cone snails are marine snails with beautiful cone-shaped shells and powerful venom. They are slow-moving predators that use a harpoon-like tooth to catch prey, so wild cone snails should never be picked up or handled.

Crab is a common name used mainly for true crabs in the infraorder Brachyura, a huge group of decapod crustaceans with broad bodies and short abdomens folded beneath the shell. True crabs inhabit every ocean and have also colonized rivers, lakes, caves, mangroves, beaches, forests, and other land habitats. They range from tiny pea crabs to Japanese spider crabs with enormous leg spans. Hermit crabs, king crabs, porcelain crabs, and several other crab-shaped animals belong to different branches.

Crayfish are freshwater decapod crustaceans closely related to lobsters. They are also called crawfish, crawdads, or freshwater lobsters in different regions. Hundreds of living species inhabit streams, rivers, lakes, swamps, caves, temporary pools, and burrows across many parts of the world. Crayfish have a hard exoskeleton, two large claws, four additional pairs of walking legs, feathery gills, long antennae, swimmerets, and a muscular tail used for rapid backward escapes.

Crickets are chirping insects related to grasshoppers and katydids. They are known for long antennae, strong jumping legs, nighttime songs, and males that make music by rubbing parts of their front wings together.

Crown-of-thorns starfish are large spiky sea stars found on coral reefs. They eat coral polyps and have venomous thorn-like spines, so they should be watched from a safe distance and never touched.

Cuttlefish are clever sea animals related to octopuses and squid. They can change color and pattern, use ink to escape, and have a special internal shell called a cuttlebone.

Damselflies are slender predatory insects in the suborder Zygoptera and the order Odonata. They live on every continent except Antarctica and are especially common near ponds, streams, marshes, and lakes. Adults have two pairs of similarly shaped wings, widely separated compound eyes, six spiny legs, and long narrow abdomens. Their young stages, called nymphs or naiads, live underwater and usually carry three leaf-like gills at the end of the abdomen.

Decorator crabs are marine crabs that hide by attaching bits of algae, sponge, shell, or other ocean material to their bodies. Their disguise can help them blend into reefs, tide pools, or seafloor habitats.

Dinomischus was a tiny stalked animal that lived attached to the Cambrian seafloor. It looked a little like a flower, with a cup-shaped body held above the mud by a slender stem and surrounded by a ring of plate-like bracts. It probably filtered tiny food particles from seawater, and recent studies suggest that Dinomischus may belong near the early evolutionary branch of comb jellies.

Diving beetles are aquatic beetles that live in ponds, lakes, marshes, and slow water. Many are strong swimmers with flattened bodies and paddle-like hind legs, and both adults and larvae are hungry predators.

Dragonflies are fast flying insects with long bodies, huge eyes, and four clear wings. They often live near ponds, lakes, rivers, and wetlands because their young grow underwater before becoming adult fliers.

Dung beetles are insects that feed on animal dung, also called manure. That may sound yucky, but these beetles are amazing recyclers because they help clean up waste, return nutrients to soil, and create safe food nurseries for their young.

Earthworms are soft segmented worms that live in moist soil, leaf litter, gardens, and compost. They tunnel through the ground, eat decaying plant material, and leave behind castings that help recycle nutrients in the soil.

Earwigs are flat, slender insects known for the pincer-like forceps at the end of the body. Despite old stories about ears, earwigs do not crawl into ears on purpose. Most hide in dark damp places and come out at night.

Emperor scorpions are large black scorpions from western Africa. They have big pincers, a curved tail with a stinger, eight legs, and a quiet nighttime life in warm forests and savannas.

The European Hornet, Vespa crabro, is a large social wasp native to Europe and parts of Asia and introduced to eastern North America. It has a reddish-brown head and thorax, yellow-and-brown patterned abdomen, powerful jaws, and two pairs of clear wings. Colonies live for one season inside hollow trees, wall spaces, sheds, bird boxes, and other sheltered cavities. Workers hunt insects for larvae while adults drink sap, nectar, fruit juices, and sugary larval secretions.

Eurypterids were extinct aquatic arthropods often nicknamed sea scorpions. They were not true scorpions, dinosaurs, fish, or reptiles, but relatives of the chelicerate group that includes spiders, scorpions, and horseshoe crabs. Some eurypterids were small, while a few giant species became some of the largest arthropods ever.

Fiddler crabs are small shore crabs often seen on mudflats, mangroves, salt marshes, and sandy beaches. Males are famous for one oversized claw that they wave to communicate, attract females, and warn other males.

Fireflies are soft-bodied beetles famous for glowing at night. They are also called lightning bugs, and many use flashing lights from their abdomens to find mates or send signals in warm fields, gardens, forests, and wetlands.

Fleas are tiny wingless insects best known for jumping and feeding on blood from animals. They have flat bodies, strong legs, and a complete life cycle that goes from egg to larva to pupa to adult.

Flies are insects in the enormous order Diptera, a name meaning two wings. The group includes house flies, hoverflies, mosquitoes, midges, crane flies, robber flies, fruit flies, blow flies, horse flies, and thousands of less familiar forms. Most adult flies use one pair of front wings for flight, while the hindwings have become tiny balancing organs called halteres. Flies live worldwide in almost every terrestrial and freshwater habitat, and their feeding habits range from nectar drinking and pollination to predation, decomposition, plant feeding, and blood feeding.

Fruit flies are tiny two-winged insects often found near ripe or fermenting fruit. Some are called vinegar flies, and one species, Drosophila melanogaster, is famous in science because it has helped researchers learn about genes, growth, and inheritance.

The Giant Centipede, Scolopendra gigantea, is also called the Amazonian Giant Centipede or Peruvian Giant Yellow-Leg Centipede. It is the world's largest well-documented living centipede and can reach about 30 centimetres in length. Verified native records come from northern South America and southern Caribbean islands. This flattened nocturnal predator hides in damp leaf litter, caves, rotting wood, rock cracks, and sheltered buildings. It uses powerful venom-delivering forcipules to capture insects, spiders, frogs, lizards, mice, and even bats.

Giant clams are huge reef mollusks with two heavy shells and colorful mantles. They live in warm Indo-Pacific coral reefs and share a clever partnership with tiny algae that help feed them with sunlight-made food.

Giant isopods are enormous deep-sea crustaceans that look like huge pill bugs from the ocean floor. They have armored plates, 14 walking legs, big eyes, long antennae, and a scavenger lifestyle in the dark deep sea.

Giant squid are mysterious deep-sea animals with huge eyes, eight arms, two extra-long tentacles, a beak, and a soft body. They live far below the ocean surface, where humans rarely see them alive.

Glowworm is a common name for several unrelated insects that produce visible light. In Europe and much of Asia, the best-known glowworms are firefly beetles in the family Lampyridae, especially wingless glowing females and predatory larvae. In New Zealand and parts of Australia, glowworms are luminous larvae of fungus gnats in the genus Arachnocampa. Beetle glowworms often shine to attract mates, while cave-dwelling fungus-gnat larvae use blue-green light above sticky silk threads to lure tiny flying prey.

Gnat is a loose common name for many tiny flies rather than one scientific group. The word often includes fungus gnats, wood gnats, gall gnats, black flies, biting midges, non-biting midges, and eye gnats from several different families. Like other true flies, adult gnats have six legs, one functional pair of wings, and balancing organs called halteres. Their larvae may live in soil, fungi, rotting wood, plants, streams, ponds, mud, or other damp places, where they act as decomposers, predators, plant feeders, and food for larger animals.

Goliath beetles are giant scarab beetles from tropical African forests. They are among the heaviest insects on Earth, especially as chunky larvae, and adults have strong legs, hard wing covers, and bold patterns.

Grasshoppers are jumping insects found in grasslands, forests, gardens, farms, and many other habitats. They are known for powerful hind legs, plant-eating habits, chirping sounds, and young nymphs that look like smaller wingless adults.

Hallucigenia was a tiny spiky animal from the Cambrian Period. It was not a dinosaur, fish, or reptile, but an extinct worm-like animal related to velvet worm relatives. Hallucigenia became famous because early scientists were not sure which side was up, which end was the head, or how its strange body worked.

Harvestmen are arachnids in the order Opiliones, also called daddy longlegs in many places. More than 6,660 living species are scientifically described, and many more probably remain undiscovered. Some have thread-like legs many times longer than the body, while others are short-legged, armored, brightly colored, or almost mite-like. Unlike spiders, harvestmen have a broad connection between the front and rear body regions, no silk glands, and no venom glands. They occur on every continent except Antarctica.

Hercules beetles are giant rhinoceros beetles famous for their huge size and dramatic horns on males. They live in tropical forests, start life as grubs in rotting wood, and grow into armored beetles with hard wing covers.

Hermit crabs are crustaceans with soft curved abdomens that need protection. Many live inside empty snail shells, changing to larger shells as they grow, while using pincers, antennae, legs, and careful shell shopping to survive.

Honey bees are social insects that live together in busy colonies. They collect nectar and pollen from flowers, make honey, build wax combs, and help pollinate many plants as they fly from bloom to bloom.

Hornets are large social wasps that live in colonies. They are known for strong flight, yellow or brown markings, paper-like nests, queens, workers, drones, and stingers that help them defend their homes.

Horseshoe crabs are ancient-looking sea animals with hard horseshoe-shaped shells, long pointed tails, and blue blood. Even though they are called crabs, they are not true crabs and are more closely related to spiders and scorpions.

Houseflies are common insects often found near people, food scraps, garbage, and animal waste. They are true flies with one main pair of wings, fast movements, big eyes, and a life cycle that goes from egg to maggot to pupa to adult fly.

Hoverflies, also called flower flies or syrphid flies, are true flies in the family Syrphidae. More than 6,000 species occur across almost every part of the world except Antarctica. Many adults have yellow-and-black markings that resemble bees or wasps, but hoverflies have only one functional pair of wings and cannot sting. Adults often drink nectar and eat pollen, making them important pollinators. Their larvae lead astonishingly different lives as aphid predators, decomposers, plant feeders, aquatic filter feeders, or guests inside ant and social-insect nests.

Insects are six-legged invertebrates in the class Insecta and form the most species-rich animal group known. Scientists have named about one million species, while research suggests several million more may remain undescribed. An adult insect typically has a head, thorax, abdomen, one pair of antennae, three pairs of legs, an exoskeleton, and compound or simple eyes. Many adults have wings, but fleas, lice, worker ants, and numerous other insects are wingless. Insects occupy almost every land and freshwater habitat and perform essential jobs as pollinators, decomposers, predators, prey, soil engineers, and plant eaters.

Japanese spider crabs are giant ocean crabs with extremely long legs, spiky shells, and a spider-like look. They live in Pacific waters near Japan and are famous for having the largest leg span of any living crab.

Jellyfish are soft sea animals with jellylike bodies, no bones, and trailing tentacles. They drift through oceans around the world and use stinging cells to catch tiny prey.

Jumping spiders are small, active spiders famous for big eyes, excellent vision, and quick jumps. Instead of using sticky webs to catch prey, many jumping spiders stalk insects carefully and leap with a silk safety line behind them.

Katydids are mostly nighttime insects related to crickets and grasshoppers. Many have very long antennae, leaflike green bodies, strong jumping legs, and loud mating calls that can make summer nights feel full of tiny hidden musicians.

Krill are tiny shrimplike crustaceans that live in the ocean, often in huge groups. They may be small, but they are one of the most important foods for whales, seals, penguins, fish, squid, and many other marine animals.

Lacewings are delicate insects named for the fine network of veins in their wings. Green lacewings are especially helpful in gardens because their hungry larvae eat many tiny pests, including aphids.

Ladybugs are small beetles with round bodies, bright colors, tiny legs, and cute spots. They are also called ladybird beetles and are loved by gardeners because many ladybugs eat plant pests such as aphids.

Leeches are segmented annelid worms commonly grouped in Hirudinea or the modern order Hirudinida. Roughly 700 species live around the world in freshwater, oceans, damp forests, caves, mountains, and other habitats. Most true leeches have a strong rear sucker and a smaller front sucker, but they vary enormously in size, color, eyes, mouthparts, and diet. Some drink blood from vertebrates, while many others hunt worms, insect larvae, snails, crustaceans, or other small animals. Leeches are relatives of earthworms, not insects or flatworms.

Limpets are cap-shaped sea snails that cling tightly to rocks and other hard surfaces. This page focuses on true limpets in Patellogastropoda, an accepted major group of marine gastropods. The word limpet is also used for unrelated snails that independently evolved similar cone-shaped shells, including keyhole limpets and air-breathing false limpets. True limpets usually have one low conical shell, a broad muscular foot, a scraping ribbon called a radula, and adaptations for surviving waves, drying air, changing temperatures, and hungry predators.

Lobsters are hard-shelled crustaceans that live mostly on the sea floor. Many true lobsters have large claws, long antennae, walking legs, strong tails, and a tough outer shell that they must molt as they grow.

Locusts are special grasshoppers that can change behavior when conditions are right. They may live quietly alone, but when many gather together, they can form marching hopper bands as nymphs and flying swarms as adults.

Luna moths are large pale green moths from North America with long tail-like wing tips and beautiful eyespots. Adults live briefly, fly at night, and do not eat because their mouthparts are reduced or absent.

Mantis usually means praying mantis, a patient insect hunter with folded front legs and a triangular head. Mantises wait quietly on leaves and stems, then grab insects with lightning-fast spiny forelegs.

Mantis shrimp are colorful marine crustaceans known for amazing eyes and super-fast hunting arms. Some use club-like arms to smash prey, while others use sharp spear-like arms to grab fish and other small ocean animals.

Marrella was a tiny marine arthropod that lived about 505 million years ago and is famous from Canada’s Burgess Shale. It was not a crab, shrimp, or trilobite. Its wedge-shaped head shield carried long backward-pointing spines, while slender antennae, paddle-like head appendages, many walking legs, and delicate gills helped it move and feed just above the seafloor.

Mayflies are delicate insects with young stages that live in water. Their adults are famous for very short lives, often only hours or days, while their aquatic nymphs may spend much longer growing in streams, rivers, ponds, or lakes.

Millipedes are slow many-legged arthropods that usually live in damp leaf litter, soil, and under logs. Most eat decaying leaves and plant material, helping recycle old plant matter back into the soil.

Mites are tiny arachnids related to ticks and spiders. Many are so small that people need a microscope to see them clearly, and different mites can live in soil, water, plants, animal nests, homes, or on other animals.

Mole crabs, often called sand crabs, are small crustaceans that live in wave-washed beach sand. They burrow backward into wet sand and use feathery antennae to catch tiny food from the water rushing over them.

The Monarch Butterfly, Danaus plexippus, is famous for orange-and-black wings and one of the greatest insect journeys on Earth. North America's migratory monarchs depend on milkweed as caterpillars and nectar flowers as adults. Several short-lived generations move north in spring and summer, but a special long-lived generation can fly as far as 3,000 miles south to wintering forests in central Mexico or sheltered groves along coastal California.

Moon jellies are pale translucent jellyfish often seen in coastal waters. They have soft bell-shaped bodies, short tentacles, four petal-like shapes inside, and a gentle pulsing swim that looks like a floating moon.

Mosquitoes are tiny flying insects in the true fly group. They are famous for buzzing and biting, but their life story begins in water, where eggs hatch into wriggling larvae before becoming pupae and then adults.

Moths are winged insects in the order Lepidoptera, the same group as butterflies. About 160,000 moth species have been described, and scientists expect many more remain unnamed. Some are tiny leaf miners, others are wider than a hand, and together they fill habitats on every continent except Antarctica.

Mussels are bivalve mollusks with two shells and soft bodies inside. Some live in the ocean attached to rocks by strong threads, while freshwater mussels often live partly buried in river or lake bottoms.

Nautiluses are ancient-looking ocean animals with soft bodies, many tentacles, and beautiful spiral shells divided into chambers. They are cephalopod mollusks, which means they are related to octopuses, squid, and cuttlefish.

Nudibranchs are colorful sea slugs that live in oceans around the world. They are soft-bodied marine mollusks, often without shells as adults, and many use bright colors, strange shapes, gills, cerata, and chemical defenses to survive.

Octopuses are clever sea animals with soft bodies, eight arms, strong suckers, large eyes, and amazing camouflage. They are mollusks, not fish, and many can squirt ink to confuse predators.

Opabinia was a strange Cambrian sea animal from the Burgess Shale of Canada. It was not a dinosaur, fish, or reptile, but an extinct arthropod relative with five eyes, a flexible front proboscis, side swimming flaps, gills, and a tail fan. Its odd body helped make it one of the most famous animals of the Cambrian Period.

Orthoceras was a straight-shelled cephalopod from ancient seas. The name is often used for fossils of long, straight nautiloid shells. These animals were related to modern nautiluses, squids, and octopuses, but they lived in hard cone-shaped shells instead of soft bodies alone.

Ottoia was a predatory priapulid worm that lived on and beneath the Cambrian seafloor about 505 million years ago. It could turn a muscular, tooth-lined proboscis inside out and push it from the front of its body. Rows of hooks and spines helped the worm grip prey, move through sediment, and feed on animals such as the small shelled creature Haplophrentis.

Oysters are ocean mollusks with two shells called valves. Many oysters live attached to hard surfaces, filter tiny food from seawater, and can build rough reefs that shelter small ocean animals.

Peacock spiders are tiny jumping spiders from Australia, famous for colorful males that lift bright fan-like body parts and dance during courtship. They are small, sharp-eyed, active hunters with big personality packed into a speck-sized body.

A pill bug, often called a roly-poly, is a tiny land-dwelling crustacean rather than an insect. This page focuses on the common pill bug, Armadillidium vulgare. Its overlapping armored plates allow it to roll into a tight ball, while its modified breathing structures keep it tied to damp, sheltered places under leaves, logs, stones, mulch, and flowerpots.

“Prawn” is a common name rather than one perfectly fixed scientific group. In many biological descriptions it refers especially to shrimp-shaped decapod crustaceans in the suborder Dendrobranchiata, which have tree-like branching gills and usually release their eggs into the water. Everyday names vary by country, so some animals called prawns belong to other groups and may be called shrimp elsewhere.

Praying mantises are insects with triangular heads, big eyes, long bodies, and folded spiny front legs. They look like they are praying, but they are really waiting to grab prey with lightning-fast moves.

Rhinoceros beetles are strong scarab beetles named for the horn-like structures on many males. They can look like tiny armored rhinos, with shiny bodies, hard wing covers, and larvae that grow in rotting wood or soil.

Salps are transparent, barrel-shaped ocean animals in the tunicate group. They may resemble jellyfish, but they are chordates and are more closely related to animals with backbones than to true jellyfish. A salp draws water through its body to collect tiny food and then squirts the water out, so one simple system provides both dinner and jet-powered travel.

Sand dollars are flat ocean animals related to sea urchins and sea stars. Living sand dollars are covered with tiny spines and move slowly through sandy seafloors, while the pale “sand dollars” found on beaches are usually their dried skeletons.

Scallops are bivalve mollusks that make fan-shaped shells. Unlike many other bivalves, some scallops can swim by clapping their shells together and pushing water out in quick jets.

Scorpions are predatory arachnids recognized by their grasping pincers and segmented tails tipped with venomous stingers. More than 2,500 species live in deserts, forests, grasslands, caves, mountains, and human-altered habitats across every continent except Antarctica. Most avoid people and hunt at night by detecting tiny vibrations, but all wild scorpions should be left untouched.

Sea angels are tiny swimming sea slugs in the gastropod group Gymnosomata. Their transparent bodies and two flapping parapodia can make them look like angels with wings, but they are skilled open-ocean predators. Many hunt shelled pteropods called sea butterflies, sometimes pulling the prey from its shell with hidden grasping structures and hooks.

Sea butterflies are tiny pelagic snails commonly grouped as shelled pteropods, especially the Thecosomata. They flutter through seawater using a muscular foot divided into two wing-like parapodia. Many build thin, transparent shells and collect microscopic food with mucus webs, making them important links between plankton and larger animals such as fish and whales.

Sea cucumbers are soft, tube-shaped marine animals that crawl along the sea floor. They are echinoderms, related to sea stars and sea urchins, and many help recycle nutrients by eating tiny food bits mixed with sand or mud.

Sea hares are soft marine mollusks that look like chunky sea slugs with rabbit-ear-like tentacles. They often eat seaweed, crawl along shallow ocean bottoms, and some can release purple or reddish ink when bothered.

Sea scorpions were extinct aquatic arthropods called eurypterids. They were not true scorpions, dinosaurs, fish, or reptiles. Some lived in seas, while others lived in brackish or freshwater habitats. A few giant kinds became among the largest arthropods ever known.

Sea slug is an informal name for many soft-bodied marine gastropods, including nudibranchs, sea hares, and sap-sucking sacoglossans. They are relatives of snails, but most adults have reduced or missing shells. Sea slugs inhabit oceans worldwide and use camouflage, warning colors, chemicals, mucus, or even defenses borrowed from their food to survive.

Sea urchins are round, spiky marine animals that live on the ocean floor. They are echinoderms, which means they are related to sea stars and sand dollars, and they use tiny tube feet, spines, and a special mouth structure to move and eat.

Shrimp are small crustaceans that live in oceans, rivers, lakes, estuaries, and muddy or sandy bottoms depending on species. They have long antennae, many legs, hard outer shells, gills, and a quick backward-swimming escape move.

Silverfish are small, quick-moving insects with silvery scales, flat bodies, long antennae, and three tail bristles. They are often found indoors in dark, damp places where they nibble starchy materials like paper, paste, and old book bindings.

Land slugs are soft-bodied gastropod mollusks that have lost the large outer shell carried by a typical snail. Slug bodies evolved independently in several gastropod lineages, so the name does not describe one single branch of the family tree. Mucus, a muscular foot, retractable tentacles, and a hidden breathing pore help these animals explore damp habitats without legs.

A snail is a gastropod mollusk with an external shell large enough to protect much of its soft body. The common name includes thousands of unrelated-looking land, freshwater, and marine species. Snails glide on muscular feet, usually feed with tooth-covered radulae, and build shells from minerals released by a tissue layer called the mantle.

Spiders are eight-legged arachnids in the order Araneae. Scientists have described more than 54,000 living species, from tiny leaf-litter hunters to large tropical tarantulas, and new species continue to be named. Every spider can produce silk, but not every spider builds a prey-catching web, and the overwhelming majority pose little or no danger to people.

Squid are fast ocean mollusks in the cephalopod group. They have soft bodies, big eyes, eight arms, two longer tentacles, a beak, and a siphon that helps them jet through the water like tiny sea rockets.

Stag beetles are beetles famous for the huge jaw-like mandibles on many males. These jaws can look like deer antlers, which is why they are called stag beetles, but the larvae quietly grow in rotting wood before becoming adults.

Starfish are better called sea stars because they are not fish. They are marine invertebrates related to sea urchins and sand dollars, with arms, tube feet, spiny skin, and amazing ways to move, eat, and regrow body parts.

Stick insects are amazing insects that look like twigs, sticks, or leaves. Their long thin bodies, slow movement, and clever camouflage help them hide from birds, reptiles, and other hungry animals.

Tarantulas are large, hairy spiders found in warm places around the world. They have eight legs, fangs, venom for catching prey, sensitive hairs, and many species live in burrows where they hide during the day and hunt at night.

Termites are social insects that live in colonies with different jobs. Many termites eat cellulose from wood, dead plants, grass, or soil materials, and tiny microbes in their bodies help them digest this tough plant food.

Ticks are tiny blood-feeding arachnids related to mites and spiders. They do not jump or fly. Instead, many wait on grass, leaves, or low plants and grab onto a passing animal or person.

Trilobites were extinct marine arthropods that lived in ancient oceans for hundreds of millions of years. They were not dinosaurs, fish, or reptiles. Trilobites had hard outer shells, segmented bodies, and three lengthwise lobes that gave them their famous name.

Vampire squid are deep-sea cephalopods with dark bodies, glowing arm tips, big eyes, and webbing between the arms that looks like a little cape. Despite the spooky name, they do not drink blood and mostly feed on drifting ocean particles called marine snow.

Velvet worms are soft, ancient-looking invertebrates with many stubby legs, tiny claws, feelers, and velvety bodies. They live in damp forests and can shoot sticky slime to catch prey like a miniature creature from a secret rainforest lab.

At first glance, a viceroy butterfly can look almost exactly like a monarch. Look carefully and you may spot a black line crossing each hindwing. Scientists once taught that an edible viceroy merely copied a bad-tasting monarch, but experiments showed that viceroys have their own chemical defenses too.

Wasps are insects related to bees and ants. Some wasps live alone, while others live in colonies. Many have narrow waists, smooth bodies, strong wings, and stingers, so their nests should be watched from a safe distance.

Water striders are insects that seem to skate across the surface of ponds, streams, and quiet water. Their long water-repelling legs spread out their weight and use surface tension to keep them from sinking.

Whirligig beetles are small aquatic beetles that spin and circle across the surface of calm ponds, lakes, and streams. They are famous for divided eyes that help them watch the air above and water below at the same time.

Wiwaxia was a small, soft-bodied animal that crawled across Cambrian seafloors more than 500 million years ago. Its back was protected by overlapping scale-like sclerites and two rows of long spines, while its underside had a broad slug-like foot. A tiny toothed feeding apparatus probably scraped algae and microbial films from the seafloor, but scientists still debate whether Wiwaxia was closer to early molluscs, annelid worms, or their shared relatives.

Woodcocks are eight living species of plump, long-billed birds in the genus Scolopax and the sandpiper family Scolopacidae. Unlike many shorebird relatives, they spend much of their time in woodland, forest edge, scrub, and damp ground where mottled feathers hide them among leaves. The widespread Eurasian Woodcock and American Woodcock are the best studied, while six species live on islands or restricted parts of Asia and New Guinea. Woodcocks probe soil for earthworms and other small animals, become especially active around dusk or at night, and perform remarkable courtship flights. Exact size, calls, migration, breeding behaviour, and conservation status differ by species.

Worm is a common name for many soft, elongated animals rather than one scientific group. Familiar earthworms and leeches are annelids, but flatworms, roundworms, ribbon worms, acorn worms, peanut worms, and other worm-shaped animals belong to distant branches of the animal family tree. They live in soil, freshwater, oceans, rotting material, and inside or on other organisms. Some are decomposers, grazers, filter feeders, predators, scavengers, or parasites. This page uses earthworms as the familiar example while clearly separating traits that do not belong to every animal called a worm.

Yellow jacket, also written yellowjacket, is a North American common name for compact social wasps mainly in the genera Vespula and Dolichovespula. Most familiar species have bold yellow-and-black patterns, but some are black and white or carry different markings. They live in colonies with a queen, female workers, males, and developing young inside layered paper nests. Some species nest underground or in cavities, while others build enclosed aerial nests. Yellow jackets hunt insects, scavenge animal food, drink nectar and other sugary liquids, visit flowers, and defend their nests with repeated stings. Species, climate, nest site, colony size, diet, colour, and seasonal cycle vary, so one description does not fit every yellow jacket.