Penguins
This reading profile brings together 5 source-linked articles that reference penguins.
Explore Fauna’s source-checked field guides and research articles covering penguins, or search the species catalog below for individual species profiles.Source-linked reading
- Field guideHow penguins stay warmA penguin's waterproof outer feather surface and downy afterfeathers hold insulating air near the skin. Fat and compact shape add resistance, while countercurrent blood vessels recover heat from flippers and feet; behavior adjusts exposure, and emperor penguins share warmth in moving huddles.
- Field guideHow seabirds handle saltKidneys alone cannot efficiently excrete all the salt gained from seawater and marine prey while conserving water. Nasal salt glands actively move ions into a secretion saltier than blood; ducts carry it to the nostrils, where droplets run or are shaken from the bill.
- Field guideDensity dependence explainedCompetition, disease, predators, mate finding, cooperative defense, and habitat modification can make demographic rates depend on density. Negative effects tend to stabilize abundance, while positive effects at low density can hinder recovery. The response may be delayed and can differ among ages, habitats, seasons, and spatial scales.
- Field guideWhy birds have air sacsBird lungs do not inflate and collapse like mammalian lungs. Expanding air sacs shift air through branching bronchi and parabronchi; in the best-known pathway, fresh flow continues across gas-exchange tissue during both inhalation and exhalation, while the sacs themselves exchange little gas.
- Field guideConvergent evolution explainedCacti and some euphorbias independently evolved succulent, spiny forms in dry habitats; wings, streamlined bodies, and camera-like eyes offer other examples at different scales. Establishing convergence requires a phylogeny and evidence that similarity arose separately rather than being inherited unchanged from a common ancestor.