EctodermThe ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ektos meaning "outside", and derma meaning "skin". Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, nerves and brain).
EndodermEndoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems.
Animal embryonic developmentIn developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animalembryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell (spermatozoon). Once fertilized, the ovum becomes a single diploid cell known as a zygote.
GastrulationGastrulation is the stage in the early embryonic development of most animals, during which the blastula (a single-layered hollow sphere of cells), or in mammals, the blastocyst, is reorganized into a two-layered or three-layered embryo known as the gastrula, with an infold named the blastopore.
CtenophoraCtenophora (; from Ancient Greek κτείς (kteis) 'comb' and φέρω (pherō) 'to carry') or ctenophores (), commonly known as comb jellies, is a basal phylum of marine invertebrate animals notable for their unique aquatic locomotion using groups of cilia (commonly referred to as "combs"). They inhabit marine habitats worldwide, with 186 recognised living species.
SpongeSponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'). They are filter feeders that are typically bound to the seabed, being sessile. Sponges are one of the most ancient members of living seabed community (macrobenthos), with many species being important reef-builders. Some sponge species inhabit freshwater.Mesohyl
CnidariaAquatic animal phylum having cnidocytesPacific sea nettles, Chrysaora fuscescensCnidaria ( ) is a phylum of animals containing over 11,000 species of aquaticinvertebrates found both in freshwater and marine environments (predominantly the latter), including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites.DiploblastyDiploblasty is a condition of the early embryo in which there are two primary germ layers: the ectoderm and endoderm. Diploblasts are the organisms which develop with two germ layers, and include Cnidaria and Ctenophora, formerly grouped together in the phylum Coelenterata, but later understanding of their differences resulted in their being placed in separate phyla. The endoderm allows them to develop true tissue.
Cell (biology)The cell is the basic structural and functional unit of all forms of life or organisms. The term comes from the Latin word cellula meaning 'small room'. A biological cell basically consists of a semipermeable cell membrane enclosing cytoplasm that contains genetic material. Most cells are only visible under a microscope. Except for highly-differentiated cell types (examples include red blood cells and gametes) most cells are capable of replication, and protein synthesis.
InvertebrateInvertebrates are animals that neither develop nor retain a vertebral column (commonly known as a spine or backbone), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordatesubphylumVertebrata, i.e. vertebrates. Nonetheless, almost all invertebrates belong to the monophyletic clade Protostomia, including arthropods, molluscs, annelids, and flatworms.
Symmetry in biologySymmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, the face of a human being has a plane of symmetry down its centre, or a pine cone displays a clear symmetrical spiral pattern.*As an Amazon Associate I earn from qualifying purchases.