Animals

Redbone Coonhound

Reef triggerfish

Reef triggerfish (Rhinecanthus rectangulus)

Reindeer

Reindeer (Rangifer tarandus): biology, behavior and human relationships

Remipedia

Remipedia: Blind, Cave-Dwelling Crustaceans and Their Place in Arthropod Evolution

Remora

Remora (suckerfish): biology, behavior, and host relationships

Repenomamus

Resplendent quetzal

Resplendent Quetzal (Pharomachrus mocinno)

Reticulated python

Rhabdodontidae

Rhabdodontidae — Cretaceous herbivorous ornithopods

Rhacophoridae

Rhacophoridae: Old World shrub, bush and flying frogs

Rhamphorhynchus

Rhea (bird)

Rhesus macaque

Rhesus macaque (Macaca mulatta)

Rhinatrematidae

Rhinatrematidae: the tailed or beaked caecilians of northern South America

Rhinella

Rhinella — Neotropical true toads (beaked or Rio Viejo toads)

Rhinoceros

Rhinoceros: biology, species, distribution, and conservation

Rhinoceros (genus)

Rhinoceros hornbill

Rhodesian Ridgeback

Rhombozoa

Dicyemida (Rhombozoa) — microscopic parasites of cephalopod renal appendages

Rhynchosaur

Rhynchosaur: Triassic herbivorous reptiles with distinctive beaks

Right whale

Ring-necked snake

Ring‑necked snake (Diadophis punctatus): description, range, and behavior

Ringed seal

Ringed seal (Pusa hispida)

Riodinidae

Riodinidae (metalmarks): an overview of the butterfly family

Riojasaurus

Risso's dolphin

Risso's dolphin (Grampus griseus)

River dolphin

Roach's mouse-tailed dormouse

Roach's mouse-tailed dormouse (Myomimus roachi)

Roadrunner

Roadrunner (Geococcyx): the fast-running ground cuckoo

Roar (utterance)

Roar (animal vocalization)

Roaring Lion (horse)

Roaring Lion (Thoroughbred racehorse)

Roborovski hamster

Rock dormouse

Rock dormouse (Graphiurus platyops)

Rock pigeon

Rock pigeon (Columba livia): overview, behavior, and relationship with people

Rock ptarmigan

Rock ptarmigan (Lagopus muta): Arctic and alpine grouse

Rockhopper penguin

Rodent

Rodents (Order Rodentia): Characteristics, Diversity, and Human Interactions

Roe deer

Rose-ringed parakeet

Rose-ringed parakeet (Psittacula krameri) — description, distribution and behaviour

Rotifer

Rotifers (Phylum Rotifera): microscopic aquatic animals

Rottweiler

Rough-skinned newt

Rough‑skinned newt (Taricha granulosa)

Rough-toothed dolphin

Rough-toothed Dolphin (Steno bredanensis): Oceanic Dolphin of Tropical Deep Waters

Rove beetle

Rove beetle (Staphylinidae)

Royal ghost frog

Rufous hare-wallaby

Rufous hare-wallaby (mala): appearance, range, and conservation

Rugops

Rugops — a small abelisaurid theropod of the mid‑Cretaceous