Respond to Stimuli

A stimuli is a detectable change in the environment. When an animal's sensory receptor detects a stimulus, it normally triggers a reflex.

Australian Scientists have discovered changes in insulin regulation in the platypus and the echidna. Glucagon-like peptide-1 (GLP-1) is a hormone that is in the gut of animals and humans that release insulin into the lower blood glucose. People with type 2 diabetes can't produce this hormone and therefore have an imbalance in their blood sugar. Monotremes have evolved changes in the hormone GLP-1 which could possibly prevent rapid degradation of GLP-1 in humans with type 2 diabetes which will help balance sugar levels by creating more insulin.

Adapt to Environment

When an alteration occurs in the structure of an organism that makes that organism better equipped to survive in the environment that trait is passed down through the process of natural selection.

The following video displays all of the adaptations the platypus has developed over millions of years. The Platypus section of the video starts at 9:50.

I emailed Australian Museum asking when platypuses branched off and developed the ability to lay eggs. A platypus expert responded to my enquiry saying, "The platypus has always been able to lay eggs. Monotremes are the first mammals that branched off from the reptiles. The ability to lay eggs, having an interclavicle (extra bone in the shoulder) and a pair of epicoracoids in the shoulder girdle are remains of reptilian ancestry. You can think of the monotremes, marsupials and the placental mammals as groupings that have branched off independently from the reptiles and have evolved independently from each other. According to fossil evidence, the earliest Ornythorynchid was Steropodon galmani, from the Early Cretaceous (about 130 million years ago)."

Reproduction

Reproduction is when sex cells come together to produce offspring and is essential for a species to survive. All organisms do it wether it be sexually or asexually.

During breeding season, increase in plasma and fecal progesterone have been recorded. This may have a correlation with the mass of certain reproductive organs. The exact reason for this is unknown but there are 3 hypothesis that are all likely scenarios. The 1st theory is that cells in the right uterus can't sense seasonal changes to the steroid hormones as well as the left uterus. The 2nd theory is that the right uterus has a more restricted blood supply so it doesn't have good exposure to the steroid hormones. The 3rd and last theory is that the left uterus is affected by hormones secreted by tertiary follicles and corpora lutea that perform separate from the other uterus.