YouTube - Notes - Full video and playlist - MES Science playlist
In this video, I discuss the wide variety of animals, which are multicellular eukaryotic organisms. Animals, including humans, almost universally consume organic material, breathe oxygen, and develop from a hollow sphere of cells called the blastula. Following the blastula stage, it folds inward to form the gastrula, which contains the fundamental germ layers that give rise to all tissues and organs in an animal. Approximately 97% of animal species are invertebrates, which never develop a vertebral column or spine. In contrast, vertebrates are defined by the presence of a vertebral column formed from the notochord, a flexible, cartilage-like rod present in early development. To date, 69,963 species of vertebrates have been described, including sharks, reptiles, and mammals (the group humans belong to).
Timestamps:
Animals are multicellular eukaryotic organisms and nearly all breathe oxygen, reproduce sexually, and grow from a hollow sphere of cells called the blastula: 0:00
Gastrulation is the phase where the blastula is reorganized into multiple layers: 3:36
Germ layers are primary layer of cells formed during embryonic development and give rise to all of animal's tissues and organs: 5:21
Gastrulation of a diploblast forms two layers from the single layered blastula: 7:02
Diploblasty has two primary germ layers: ectoderm and endoderm while complex animals (including humans) are triploblastic and have a mesoderm as well): 7:51
More than 1.5 million living animal species have been described, around 1 million are insects: 10:56
Food chain is a linear network of links in a food web starting from producers and ending at an apex predator, detritivores, or decomposers: 14:55
Detritivores obtain nutrients by consuming detritus or decomposing plant and animal parts as well as feces: 17:08
Decomposers break down dead or decaying organisms and carry out decomposition: 18:05
Diversity of animals photos: 20:06
Sponges are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them: 22:22
Collagen is the main structural protein in the body's connective tissues and makes up 25% to 35% of mammals' whole-body protein content: 27:02
Epithelial tissue is a thin continues layer of compactly packed cells and line the outer surfaces of organs, inner surfaces of many internal organs, and blood vessels: 28:08
97% of animal species are invertebrates, which don't develop a vertebral column or spine: 33:04
Axial skeleton of humans diagram: 36:24
Hyoid is the only bone in the human body that is not connected to any other nearby bones: 38:56
Notochord is a flexible rod formed in some animals, including humans, which formed the veritable column: 43:37
Dorsal hollow nerve cord is a hollow tube and distinguishes chordates from other animals don't have it: 47:35
Pharynx is part of the throat behind the mouth and nasal cavity and above the esophagus: 49:10
Larynx or voice box is in the top of the neck involved in breathing, producing sound, and protecting the trachea against food aspiration: 51:34
Spinal cord is nervous tissue which extends from the brainstem to the bottom region of the vertebral column: 52:58
Spinal cord connects the brain to nerves throughout the body: 55:23
Vertebrates represent almost all chordates, with 69,963 species described: 56:43
Amphibians are ectothermic (have very low internal heat generation) and live in a wide variety of habitats, with most start out as larvae living in water: 58:07
Animal Diversity: Sponges, Chordates, Vertebrates, Blastulation, Food Chain