Hydra was a many headed serpent in Greek mythology
The Hydra?? I think you may be referring to the Lernaean Hydra, which by varying accounts has as few as 5 and as many as 100 heads. 9, however, is the accepted standard.
how many tissue layers do the phylum arthropoda have
A hydra typically has two cell layers: an outer layer of epithelial cells and an inner layer of gastrodermal cells. These layers are separated by a jelly-like extracellular matrix called the mesoglea.
There are three layers of embryonic tissue present in the pig. These layers are called the ectoderm, mesoderm and the endoderm.
Three
There are three layers: ectoderm, mesoderm, and endoderm.
Phylum Platyhelminthes have three tissue layers: ectoderm, mesoderm, and endoderm.
The Hydra was born from the blood of the monster Typhon when he was wounded by the god Hercules. It is a serpent-like creature with multiple heads that grow back when cut off, making it a formidable adversary in Greek mythology.
three
3
Four layers of tissue form the walls of the digestive tract. These layers are called mucosa, submucosa, muscularis externa and adventitia.