Why do flatworms not have a Coelom?
Flatworms, lacking a coelom, were traditionally thought to represent leftovers from the early days of animal evolution, before any animals had a coelom. The author suggests that modern flatworms descended from a coelomate ancestor, which lost its coelom (and its anus!) through the course of evolution.
What type of symmetry do flatworms possess?
Flatworms are flattened and have bilateral symmetry. They are triploblastic (have 3 embryonic tissue layers: ectoderm, mesoderm, and endoderm) and therefore have organ-level of organization. There is no body cavity, so they are acoelomate.
Are all flatworms bad?
Active Member. Run of the mill flatworms aren’t really that bad unless they reach plague proportions and start blocking the light from your corals. That said, they can irritate acros if they’re hanging out on them in large amounts, even if they aren’t AEFW.
What are the disadvantages of a flatworms digestive system having?
The main disadvantage of a digestive system like this is that there is only one opening where the food enters and leaves. Therefore the organism, in our case, the flatworm, must wait for the food to be digested and excreted through the opening in order to be able to eat again.
Do Cnidaria have a digestive system?
Cnidarians carry out extracellular digestion, where enzymes break down the food particles and cells lining the gastrovascular cavity absorb the nutrients. Cnidarians have an incomplete digestive system with only one opening; the gastrovascular cavity serves as both a mouth and an anus.
What is a Spongocoel Is it a true digestive system?
They do not have a digestive system nor do they release digestive enzymes in the spongocoel to cause extracellular break down of nutrients. is reproduction in sponges sexual or asexual? Basic morphology: tubular or globular body with spongocoel, sessile; choanocytes, pinacocytes and amoebocytes.
Where do sponges digest?
Sponges do not have a digestive system. Digestion is simple and takes place by intracellular digestion. Their food is trapped as water passes through the ostia and out through the osculum in the canal system pathway.
Do sponges have sexes?
Most sponges are hermaphrodites (function as both sexes simultaneously), although sponges have no gonads (reproductive organs).