What type of symmetry does a sponge have?
Most animals are bilaterally symmetrical with a line of symmetry dividing their body into left and right sides along with a “head” and “tail” in addition to a top and bottom. Only sponges (phylum Porifera) have asymmetrical body plans.
Do sponges have a Gastrovascular cavity?
Sponges are unsymmetrical or radially symmetrical, with many cell types but no distinct tissues; their bodies contain numerous pores and sharp protective spicules. Coelenterates (phylum Cnidaria) are radially symmetrical, with two tissue layers (ectoderm and endoderm) surrounding an all-purpose gastrovascular cavity.
Which characteristic is used to classify a sponge?
Sponges are the simplest multicellular organisms, classified by their primitive cellular-level of organization, their porous bodies, and their filter-feeding system. Sponges have specialized cells that can carry out distinct functions within the organism.
How does cnidarian digestion compare with that of the sponge?
Sponges have multiple cell types that are geared toward executing various metabolic functions. Cnidarians have outer and inner tissue layers sandwiching a noncellular mesoglea. Cnidarians possess a well-formed digestive system and carry out extracellular digestion.
What opening the cnidarians use to remove the waste?
The cnidarian digestive cavity, called the coelenteron, has a single mouth opening through which food/prey enters and waste is expelled.
Do jellyfish have true tissues?
Although they have specialized cells for particular functions, they lack true tissues in which specialized cells are organized into functional groups. The cnidarians, or the jellyfish and their kin, are the simplest animal group that displays true tissues, although they possess only two tissue layers.
Are platyhelminthes tissue true?
Porifera (sponges) have specialized cells and an endoskeleton but lack true tissues and body symmetry. Platyhelminthes (flatworms) have a mesoderm cell layer, simple organ systems, cephalization, and bilateral symmetry.
What is a Nematocyst for what purpose s are they used?
Abstract. Nematocysts or cnidocysts represent the common feature of all cnidarians. They are large organelles produced from the Golgi apparatus as a secretory product within a specialized cell, the nematocyte or cnidocyte. Nematocysts are predominantly used for prey capture and defense, but also for locomotion.
What are 4 functions of nematocysts?
Nematocysts are used by organisms for prey capture and feeding, but also for defense, transport, digestion and other various functions [3, 4].
What does Nematocyst mean?
: one of the stinging capsular organelles of the tentacle of a cnidarian (such as a box jellyfish or sea anemone) that contains a coiled, hollow, usually barbed, venomous thread which is discharged especially for catching prey and defending against enemies Each nematocyst contains a spiral-coiled thread tipped with a …
How do humans use cnidarians?
Human uses: All kinds of corals hard and soft, sea anemones and other cnidaria are extensively harvested from the wild for the live aquarium trade. Hard coral are also mined as building materials in some coastal areas. Living coral reefs, however, are worth far more to humans when they left alone.
How do humans place the survival of cnidarians in danger?
Humans place the survival of cnidarians in danger through reclamation, pollution, tramplings, and poaching.
What cnidarians do?
Cnidaria (/nɪˈdɛəriə, naɪ-/) is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey.
What causes a Nematocyst to discharge?
A nematocyst consists of a capsule containing a coiled tubule. On triggering, the cyst extrudes this tubule in an extremely rapid manner. This causes an increase in the pressure of the matrix against the cyst wall. We suggest that this nonosmotic pressure increase causes the first and extremely rapid step of discharge.
What happens after a Nematocyst is discharged?
Penetrant: The penetrant or stenotele is the largest and most complex nematocyst. When discharged, it pierces the skin or chitinous exoskeleton of the prey and injects the venomous fluid, hypnotoxin, that either paralyzes the victim or kills it.
What is inside a Nematocyst?
Each is produced by a special cell called a cnidoblast and contains a coiled, hollow, usually barbed thread, which quickly turns outward (i.e., is everted) from the capsule upon proper stimulation. The purpose of the thread, which often contains poison, is to ward off enemies or to capture prey.
What are the two main locations of nematocysts?
Cnidarians contain specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts (stingers). These cells are present around the mouth and tentacles, and serve to immobilize prey with toxins contained within the cells. Nematocysts contain coiled threads that may bear barbs.
What is the difference between Cnidocyte and Nematocyst?
A cnidocyte is present on the skin of the creature (on the tentacles in the case of jellyfishes) whereas a nematocyst is present inside the cnidocyte. A cnidocyte is like an inverted cell whereas a nematocyst is a bag-like and globular structured subcell.
What are stinging cells called?
Where are nematocysts found?
What are the three types of nematocysts?
There are three main types of cnidae: nematocysts, ptychocysts, and spirocysts, with many variations. Depending on the species, one or more types may be on the organism. Nematocyst. This is the main type, present in all Anthozoa.
What are the two body forms of cnidaria?
Cnidarian body forms. Cnidarians have two distinct body plans, the medusa (a) and the polyp (b). All cnidarians have two membrane layers, with a jelly-like mesoglea between them.
Why is a jellyfish called a Medusa?
A jellyfish is called a Medusa The shape of this bell is called a medusa because it looks like the evil Medusa in Greek mythology – a woman who had offended the goddess Athena who then changed her hair into snakes and made her face so hideous it turned people into stone.
Is Aurelia a polyp or medusa?
Aurelia undergoes alternation of generations, whereby the sexually-reproducing pelagic medusa stage is either male or female, and the benthic polyp stage reproduces asexually….Aurelia (cnidarian)
|Adult Aurelia aurita medusa|
What is the largest class of cnidarians?