Like the cnidarians, flatworms have
a digestive system with
only a single opening into the digestive cavity, but in independently living marine flatworms the cavity branches into all parts of the body (Fig. … Undigested food passes back out through the mouth, as in the cnidarians.
What do platyhelminthes and cnidarians have in common?
Cnidarians are diploblastic, whereas Platyhelminthes are triploblastic. Platyhelminthes possess
bilaterally symmetrical, soft, worm-like elongated bodies
, whereas cnidarian possess radially symmetrical, soft, medusa-like or polyp-like body forms. Cephalization is present in Platyhelminthes, but not in cnidarians.
Answer: The answer is D:
a digestive system with a single opening
. Cnidarians and flatworms have a digestive system with a single opening.
Are cnidarians flatworms?
Cnidarians include jellyfish and corals. They are aquatic invertebrates. … Many corals secrete an exoskeleton that builds up to become a coral reef. Platyhelminths are
flatworms
such as tapeworms and flukes.
Answer: The answer is D:
a digestive system with a single opening
. Cnidarians and flatworms have a digestive system with a single opening.
Do flatworms have a circulatory system?
Flatworms have no circulatory system
. Animals without a circulatory system have limited abilities to deliver oxygen and nutrients to their body cells because of the way that molecules behave. As molecules spread through water, they become less concentrated as they move away from their source.
What organ systems do flatworms have?
Flatworms are hermaphroditic and capable of sexual and asexual reproduction. Their bodies have only a single opening, which serves as both a mouth and an anus. They are, as their name implies, flat. They have no circulatory system or body cavity (coelom), but they do have
an excretory and digestive system
.
What do Platyhelminthes have that Poriferians and/or cnidarians don t?
Porifera (sponges) have specialized cells and an endoskeleton but
lack true tissues and body symmetry
. Cnidaria (jellyfish and corals) have tissue-level organization and radial symmetry. Platyhelminthes (flatworms) have a mesoderm cell layer, simple organ systems, cephalization, and bilateral symmetry.
Is a flatworm a parasite?
Flatworm, also called platyhelminth, any of the phylum Platyhelminthes, a group of soft-bodied, usually much flattened invertebrates. A number of flatworm species are free-living, but
about 80 percent of all flatworms are parasitic
—i.e., living on or in another organism and securing nourishment from it.
Summary: One of the world’s strangest creatures has found its long-lost kin. Oxford University scientists have discovered that
an extremely rare gutless worm is related to sea anemones and jellyfish
, rather than similar-looking animals, reports the journal Science.
How do flatworms reproduce?
Flatworms are hermaphroditic (having both male and female sex organs) and they typically reproduce both sexually and asexually. The majority of sexual reproduction is
through cross-fertilization
(where both individuals fertilize each other).
What were flatworms the first to possess?
The ancient flatworms were the first animals to
develop a central nervous system and a head with a brain
. The head had eyes—the first in the animal world.
What characteristics do flatworms have?
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. Flatworms have a gastrovascular cavity with one opening (a sac-like gut).
How do flatworms detect light?
Flatworms have unusual ciliary cells outside their eyes which
use a newly discovered protein to detect light
. Eyes are elaborate organs that many animals use to detect light and see, but light can also be sensed in other, simpler ways and for purposes other than seeing.
What is the difference between a free living and a parasitic flatworm?
The free-living species of flatworms are
predators or scavengers
. Parasitic forms feed on the tissues of their hosts. Most flatworms, such as the planarian shown in Figure 1, have a gastrovascular cavity rather than a complete digestive system.
How are cnidarians classified?
Cnidarians are classified into four main groups:
non-moving
(sessile) Anthozoa (sea anemones, corals, sea pens); Cubozoa (box jellies);swimming Scyphozoa (jellyfish); and Hydrozoa, a broad group that includes all the freshwater cnidarians as well as many marine forms. … Cnidaria have no organs like hearts or lungs.
