Animal: Hydra
A hydra is a multicellular animal with probably the most simple immune system. It does not have a protective barrier or a mobile phagocyte. A hydra's epithelium is well prepared with potent antimicrobial peptides. This is to prevent infection or disease. The induction of antimicrobial peptide production is controlled by the interaction of a leucine-rich repeats domain containing protein. It also includes a TIR-domain containing protein not having leucine-rich repeats (LRRs). Also, Toll-like receptors (TLRs) are not in the hydra. In evolution, the epithelium was an ancient system of host defence.
The endocrine system of a hydra is also not so hard to comprehend. It has slow yet long lasting effects. This happens because there is a long distance between the effector and target cell. Also, other stimuli can cause the releas of chemial substances that serve as signals for managing food behavior in the endocrine system. Another thing is that thyroxine causes asexual reproduction through budding.
The endocrine system of a hydra is also not so hard to comprehend. It has slow yet long lasting effects. This happens because there is a long distance between the effector and target cell. Also, other stimuli can cause the releas of chemial substances that serve as signals for managing food behavior in the endocrine system. Another thing is that thyroxine causes asexual reproduction through budding.
Animal: Jellyfish
The immune system of a jellyfish is really just based on defending itself from other predators. When it is attacked, stinging threads uncoil quickly from its tentacles when it makes contact with another object. This reaction then spreads to the rest of the same tentacle making contact with the other object. Finally, the jellyfish then releases a toxin that can either paralyze or kill another predator. This action comes in handy when the jellyfish is going to consume another species.
Not much is known about the endocrine system of a jellyfish. As many know, it has no heart and is made up of mostly water (about 95%). Also it has very little protein and even fewer minerals. Jellyfish do, however, have sensory organs called rhopalia. They form a row of small round structures along the rim of the bell of a jellyfish. Inside the rhopalia, there are these things called statocysts that help the jellyfish keep its balance. When it tips too far to one side, the statocyst stimulates the nerves and causes the muscles to contract, making the jellyfish turn right side up.
Not much is known about the endocrine system of a jellyfish. As many know, it has no heart and is made up of mostly water (about 95%). Also it has very little protein and even fewer minerals. Jellyfish do, however, have sensory organs called rhopalia. They form a row of small round structures along the rim of the bell of a jellyfish. Inside the rhopalia, there are these things called statocysts that help the jellyfish keep its balance. When it tips too far to one side, the statocyst stimulates the nerves and causes the muscles to contract, making the jellyfish turn right side up.
Animal: Coral
The immune system of a coral is a bit more complex than the other two species mentioned above. A coral can recognize specific pathogens and allografts. If a coral is in a warm ocean, it could could compromise its immune system, making it liable to getting tropical marine diseases. However, a coral has the ability to fight both primary and opportunistic infections, through adaptive-like mechanisms, may play a very important role in the corals' ability to fight future diseases and infections. On simpler terms, coral can reject foregin tissue, fuse with others to survive, and help injured polyps recover over time.
Most broadcast spawning scleractinian corals synchronously release gametes during a brief annual spawning period. In southern Taiwan, the mass spawning of scleractinians occurs in lunar mid-March. Endocrine system has been proposed to play important roles in this annual phenomenon. A scleractinian coral, Euphyllia ancora has been selected as a model for the hormones and reproduction studies. We detected the presence of estradiol (E2), testosterone (T), glucuronided E2, glucuronided T, aromatase, immunoreactive (ir)GnRH in coral polyps E. ancora. Annual profiles of sex steroids, aromatase, and irGnRH have also been characterized. We found the parallel increases in irGnRH concentrations, aromatase activity and free E2 and glucuronided E2 concentrations at the time of coral mass spawning. The stimulation of mammalian (m)GnRH agonist in the increased aromatase activity and sex steroid concentrations was also observed in corals. Coral extracts (irGnRH) and mGnRH agonist had a similar dose-dependent effect on luteinizing hormone release in black porgy fish pituitary cells (in vitro). In conclusion, our data suggest that irGnRH and glucuronided E2 may play important roles in the control of reproduction and mass spawning in corals. Corals already evolved the vertebrate-type hormone system in the sexual reproduction.
Most broadcast spawning scleractinian corals synchronously release gametes during a brief annual spawning period. In southern Taiwan, the mass spawning of scleractinians occurs in lunar mid-March. Endocrine system has been proposed to play important roles in this annual phenomenon. A scleractinian coral, Euphyllia ancora has been selected as a model for the hormones and reproduction studies. We detected the presence of estradiol (E2), testosterone (T), glucuronided E2, glucuronided T, aromatase, immunoreactive (ir)GnRH in coral polyps E. ancora. Annual profiles of sex steroids, aromatase, and irGnRH have also been characterized. We found the parallel increases in irGnRH concentrations, aromatase activity and free E2 and glucuronided E2 concentrations at the time of coral mass spawning. The stimulation of mammalian (m)GnRH agonist in the increased aromatase activity and sex steroid concentrations was also observed in corals. Coral extracts (irGnRH) and mGnRH agonist had a similar dose-dependent effect on luteinizing hormone release in black porgy fish pituitary cells (in vitro). In conclusion, our data suggest that irGnRH and glucuronided E2 may play important roles in the control of reproduction and mass spawning in corals. Corals already evolved the vertebrate-type hormone system in the sexual reproduction.