It is a Period of Amazing Physiology! Can go for months without drinking, eating, urinating, defecating, or exercising Fat Tissues Water Calories Muscle and Organ Tissues Protein
We can learn a lot from bears Bears do not get dehydrated Implications for people with chronic kidney failure It is a Period of Amazing Physiology!
Denning bears have very high cholesterol levels Dissolves cholesterol gall stones, eliminating need for surgery It is a Period of Amazing Physiology! Bile juice Do not develop cholesterol gall stones Humans We can learn a lot from bears
Bears: no muscle or bone atrophy Space travel It is a Period of Amazing Physiology! We can learn a lot from bears
Do all bear species use this adaptive strategy?
Asiatic Black Bear ? Yes Denning period is similar to that of American Black Bear Enter den Nov-Dec Pregnant females give birth around Jan Emerge from den between March-April Southern Asia, Northeast China, Japan and Far Eastern Russia
Polar Bear ? Only pregnant females enter a den, give birth Nov/Dec, and emerge when cubs can trek state of “walking hibernation ” Do not overwinter in dens like brown bears and black bears Most remain active year-round Have ability to reduce their metabolic rate when food is scarce polar bears come ashore after ice melts in Hudson Bay each summer maintain normal body temps reduce metabolic rate recycle proteins
Spectacled Bear Giant Panda Bear Sun Bear Sloth Bear These bears appear to remain active year-round Although……… pregnant females build birthing dens or nests Live in areas where food sources are available year-round
Delayed Implantation ….fertilized egg divides a few times… …development STOPS! …several weeks before female enters maternity den… ….fertilized egg attaches to uterine wall…. ….cubs! If not, then embryo is reabsorbed back into female’s body Why is this reproductive strategy advantageous? Adaptive Strategy:Reproduction Female bear mates… …fertilized egg floats free in the uterus for several months … ….continues for about 8 weeks… ….development RESTARTS