The alkaline earth metals are six chemical elements in column (group) 2 of the Periodic table.They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).They have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.hey are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.
Female killer whales reach sexual maturity when they grow to about 15-18 feet (4.6 m-5.4 m) long, depending on geographic region. The gestation period for killer whales varies from 15-18 months. Birth may take place in any month--there is no distinct calving season. Calves are nursed for at least 1 year, and may be weaned between 1-2 years old. The birth rate for killer whales is not well understood, but, in some populations, is estimated as every 5 years for an average period of 25 years. Killer whales are highly social animals that occur primarily in relatively stable social groups that often range in size from 2 to 15 animals.
4. Killer Whale â 17 months. But there's a good reason for that â after that 17 months, Baby Shamu emerges weighing anywhere from 265-353 pounds and measuring about 8.5 feet long. Yikes. 5. Opossum - 12-13 days, which is one of the shortest gestation periods we know of in a mammal. But since the lifespan of an opossum is only two to four years, this makes sense. 6. Gerbils â 23-26 days. 7.