Explain how epithelial-like cells control filter feeding in sponges. Epithelial-like cells can contract and relax. This opens and closes pore cells. … Amoebocytes carry food from collar cells to all body cells, carry sperm to eggs, and produce chemicals that help make up spicules.
What does sessile sponge mean?
Adult sponges are sessile. This means they are unable to move from place to place. … Sponges are filter feeders. They pump water into their body through their pores.
Why are sessile stationary organisms usually filter feeders?
Why are filter-feeders usually stationary organisms? Filter feeders can remain sessile as their food comes to them. The tidal currents allow new food (in the form of bacteria and algae) to drift by. … Because of this, filter feeders to not require movement to obtain food or evade predators.
How is swimming accomplished by the medusa?
The medusa is a free-swimming form; it moves by rhythmic muscular contractions of the bell, providing a slow propulsive action against the water. The other principal body type of the adult cnidarian is the polyp, a stalked, sessile (attached) form.
What is the function of Cnidocytes?
Cnidocytes (‘stinging cells’) are specialized cells that define the phylum Cnidaria (sea anemones, jellyfish, corals and hydras). They contain an “explosive” organelle called cnidocyst that acts as a 600 million-years-old microscopic injection system and is important for prey capture and anti-predator defense.
What is the function of nematocyst?
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 the 4 functions of nematocysts?
Nematocysts are used by organisms for prey capture and feeding, but also for defense, transport, digestion and other various functions .
What three things are Cnidocytes used for?
A cnidocyte is an explosive cell containing one giant secretory organelle or cnidae that defines the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.). Cnidae are used for prey capture and defense from predators.
Does Hydra have medusa stage?
Unusual because in Hydra there is no medusa. Hydra can reproduce sexually. Look for ovaries near the base, testes higher on the column. Once fertilized, this egg develops a protective ornamented shell and frequently enters a stage of arrested development or dormancy.
What is the advantage of the medusa form?
The Medusas Stage allows for the cnidarians to actively move using their long tentacles to pull the water into themselves to gain nutrients.
Is Hydra a polyp or medusa?
Hydra exists in both forms: Polyp and Medusa. These forms are dependent upon nutritional content of the living environment. Medusa is the adult and sexual form whereas Polyp is juvenile and asexual form. Under harsh living conditions and starvation, hydra reproduces sexually.
Are all filter feeders sessile?
Some filter feeders are sessile organisms – they don’t move much, if at all. Examples of sessile filter feeders are tunicates (sea squirts), bivalves (e.g. mussels, oysters, scallops), and sponges. Bivalves filter-feed by straining organic matter from the water using their gills.
What does it mean to be a sessile filter feeder?
Sessile means “permanently attached” typically under water to the seafloor. … Filter feeders are animals that eat by filtering/straining food floating in sea water.
Why do baleen whales are called filter feeders?
Whales called as filter feeders because they used to filtered their food through baleen plates. they suction water into their mouths at high velocities while their body remains stationary. The food along with water moves through the filtering pads or baleen plates that covered the entrance of their throat.
Why are jellyfish called 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.
Are jellyfish polyps or medusa?
Jellyfish have a stalked (polyp) phase, when they are attached to coastal reefs, and a jellyfish (medusa) phase, when they float among the plankton. The medusa is the reproductive stage; their eggs are fertilised internally and develop into free-swimming planula larvae.
Is a medusa free living?
Within the Cnidaria are free-living forms (the medusae or jellyfish) and fixed forms (polyps).
Can we see Hydra?
The constellation Hydra, the sea serpent, is best seen from the southern hemisphere, but can be observed in the north between January and May. It is visible at latitudes between 54 degrees and -83 degrees. It is the largest constellation in the night sky, covering an area of 1,303 square degrees.
Do corals have a medusa stage?
The class Anthozoa includes all cnidarians that exhibit a polyp body plan only; in other words, there is no medusa stage within their life cycle. Examples include sea anemones, sea pens, and corals, with an estimated number of 6,100 described species.
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.
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.