January 11, 2011. 1  According to Education Next, teachers retire, on average, at around the age of 58. AARP reports that 33 percent of all beginning teachers leave the teaching profession within three years of beginning their careers, but the majority of teachers continue teaching and can reap retirement benefits later in life.
Deep-sea anglerfish, hatchetfish, and lantern fish are among the best-known luminescent fishes. In most such fishes, luminescence is produced intracellularly; the light is emitted by special cells called photocytes. The anatomical structure of the luminous organs of many fishes is similar to that of squids.
In cichlid tanks, you can avoid problems with your fish uprooting your plants by using floating plants that do not need to be rooted in substrate at all. Some popular species of floating plants include duckweed, hornwort, crystalwort and azolla.