Write an essay on parental care in mammals
What are the benefits of parental care? The importance of parental effects on developmental rate
I was absolutely enthralled by the intricacy of the biological systems that made a new person: wombs, placentas, mammary glands…. That seemed to be the theme linking my fascinations.
Mammals are named after the mammary gland, but mammalian evolution was associated with many reproductive innovations. With mammalian-ness being the link between these traits, I wondered if I might produce a book by writing a series of connected essays about all the traits that made a mammal a mammal.
A book that would make the case that our mammalian heritage is central to how we live. To start the project, I wrote out a list of the main distinguishing features of mammals — those mammary glands; hair and warm blood; our particular cerebral cortex; three bones in our middle ears and unique jaw joint; the diaphragm, and so on….
Parental Care in Fishes | Zoology
Those were basically my chapter headings, and the exact things that we have in common with other mammals. Initially, I just listed the traits and set to writing a chapter about each. In the last chapter, I try to think about what exactly defines a mammal. There were many. Some small, some large.
Frog Reproduction, from Mating to Metamorphosis
There are various approaches to reproduction. Put crudely, you can either produce lots and lots of cheap offspring, put very little effort into parental care, and hope that a small fraction of the many make it.
Or you can have far fewer offspring and invest very heavily in each. The effects of this span the emergence of mammalian wombs through to young mammals learning key skills from their parents. This really resonated with my experience of parenthood. Well, yes and no.
No, in the sense that it really is about all that we humans share with the other five-and-a-half thousand species of mammals kicking about this globe. Both birds and mammals are warm-blooded, which means they can maintain a constant body temperature and do not need to rely on an external heat source to stay warm.
This similarity lends itself to several other commonalities, such as similar caloric requirements by weight and the ability to remain active in colder temperatures. Cold-blooded animals, such as reptiles, do not have to eat as much, but they also cannot survive colder temperatures. Being warm-blooded also gives birds and mammals the unique ability to live on any landmass on Earth.
All mammal and bird species are classified as vertebrates, meaning they have backbones and skeletal systems made of bone. Birds, however, have hollow bones with a crisscrossed matrix for added strength. The hollow bones are lightweight, which allows the bird to take flight, while the structural matrix adds strength to withstand the pressure of taking off and landing.
Birds require a lot of energy in order to fly. This also necessitates a circulatory system that is both efficient and effective, so they have evolved a four-chambered heart with two atria and two ventricles, just like mammals.
One of the main benefits of this type of circulatory system is that it allows the separation of oxygenated and deoxygenated blood. Other species of animals, such as reptiles, have hearts with fewer chambers, which means both oxygenated and deoxygenated blood have to travel through some of the same chambers — a much less efficient model. The blood of birds and mammals contains both red and white blood cells, called erythrocytes and leukocytes respectively.