Bird anatomy Birds have a four-chambered heart, in common with mammals, and some reptiles (mainly the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A ruby-throated hummingbird's heart beats up to 1200 times per minute (about 20 beats per second). Many birds possess a muscular pouch along the esophagus called a crop. The crop functions to both soften food and regulate its flow through the system by storing it temporarily. The size and shape of the crop is quite variable among the birds. Members
Retort pouch in 1992. Retort pouches are used in field rations, space food, fish products camping food, instant noodles, and brands such as Capri Sun and Tasty Bite. Some varieties have a bottom gusset and are known as Stand-Up Pouches. The retort pouch was invented by the United States Army Natick R&D Command, Reynolds Metals Company, and Continental Flexible Packaging, who jointly received the Food Technology Industrial Achievement Award for its invention in 1978. Retortable pouches are extensively used by the U.S. military for field rations (called "Meals, Ready-to-Eat", or "MREs"). A retort pouch is constructed from a flexible metal-plastic laminate that