Portuguese Man-Of-War and Blue Bottle

The Portuguese Man-of-war has dozens of tentacles, which carry enough venom to paralyze a swarm of fish instantly, and entanglement in the tentacles can mean rapid death for even a healthy person.

The Portuguese Man-of-war (Physalia physalis) and the Blue Bottle (Physalia utriculus) are as fascinating as they are dangerous. They are related, but the Blue Bottle is smaller and is seemingly less ferocious. Their most noticeable feature is the exquisitely blue jelly or float. The floating part is filled with gas, which causes it to rise to the surface. The Physalia physalis’s float grows up to 30 cm (12 in) long, while the Physalia utriculus’s float grows less than 10 cm (4 in) long and is more typically less than 5 cm (2 in) long. When suspended, the float remains above the water, raising the tentacles as fishing lures. These creatures are blown ashore in vast armadas in tropical and subtropical regions during the warmer months. Each “individual” is a colony. They are either right- or left-oriented regarding how the float aligns with the rest of the body. In the middle of the open ocean where Physalia lives and breeds most of the time, the left- and right-oriented colonies are more or less equally mixed. When a breeze stirs up and pushes the Man-of-war and Blue Bottle toward land, only those with the float facing the correct way for catching the breeze will be engaged. If the breeze is sustained, the wind will carry them until they become stranded on land, where most will perish. Scientists theorize that having right- and left-oriented forms offers a higher survival chance, as part of the population is left behind to  keep the species alive.