Types of Biological Rhythms

What is a circadian rhythm?

is a biological process that follows a roughly 24-hour cycle, influencing activities like feeding, sleeping, and hormone release.

What are tidal rhythms?

are cycles based on the tides, usually with two high and two low tides per day. Organisms synchronize activities to these cycles, often using hydrostatic pressure as a cue.

What are monthly (circamonthly) rhythms?

occur about once every 29–30 days. An example is the Ant Lion (Myrmeleon obscurus), which exhibits monthly patterns of activity.

What are annual (circannual) rhythms?

are biological cycles that occur once a year, often related to reproduction, migration, or hibernation.

Some birds display migratory restlessness (Zugunruhe) even in captivity, showing these rhythms are internally controlled.