How the sea anemone obtains its food?
“How do they feed?” Anemones have rings of tentacles surrounding their central mouth. Tentacles have specialised stinging cells called nematocysts. They use these to immobilise their prey so that the tentacles are then able to move the food into the mouth.
During which two stages does embryonic development take place?
The process of prenatal development occurs in three main stages. The first two weeks after conception are known as the germinal stage, the third through the eighth week is known as the embryonic period, and the time from the ninth week until birth is known as the fetal period.
Which of the following organisms has a colonial body form made up of individual polyps?
Cnidarians have two body forms—polyp and medusa—which often occur within the life cycle of a single cnidarian. The term polyp also is sometimes applied to an individual in a colony of invertebrate aquatic animals belonging to the phylum Bryozoa, although those individuals are usually called zooids.
What is the beneficial living arrangement between the coral polyps and the tiny algae within them known as?
Most reef-building corals contain photosynthetic algae, called zooxanthellae, that live in their tissues. The corals and algae have a mutualistic relationship.
What are the two main body forms of a cnidarian?
They have a simple body consisting of a central gut cavity surrounded by tentacles. A jelly-like substance called mesoglea lies between the outer and inner layers of the body. There are two basic cnidarian body shapes: a polyp form, which is attached to a surface; and an upside-down free-floating form called a medusa.
What is the advantage of a partitioned Gastrovascular cavity?
What is the advantage of a partitioned gastrovascular cavity? The partitioning of the gastrovascular cavity increases its surface area for a greater rate of absorption.
Does Gastrovascular cavity have one opening?
Gastrovascular cavities, as shown in Figure 1a, are typically a blind tube or cavity with only one opening, the “mouth”, which also serves as an “anus”. From the gizzard, the food passes through the intestine, the nutrients are absorbed, and the waste is eliminated as feces, called castings, through the anus.
What is the difference between a Gastrovascular cavity and a complete digestive system?
The key difference between gastrovascular cavity and alimentary canal is that gastrovascular cavity is a two-way digestive tract which has only one opening while the alimentary canal is a one-way digestive tract which has two openings.
What is special about the Gastrovascular cavity of platyhelminthes?
The gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Coelenterates or cnidarians (including jellyfish and corals) and Platyhelminthes (flatworms). The cavity may be extensively branched into a system of canals.
What is unique about the digestive system in platyhelminthes?
Flatworms have no true body cavity, but they do have bilateral symmetry. Due to the lack of a body cavity, flatworms are known as acoelomates. Flatworms have an incomplete digestive system. This means that the digestive tract has only one opening.
What is the advantage of Cephalization in flatworms?
The mouth is also located near the front of the creature. Advantages of cephalization are development of a complex neural system and intelligence, clustering of senses to help an animal rapidly sense food and threats, and superior analysis of food sources. Radially symmetrical organisms lack cephalization.
What do you notice about the shape of flatworms How is this shape beneficial?
What do you notice about the shape of flatworms? How is this shape beneficial? Their shape allows the species to survive without a circulation system to deliver oxygen and remove waste from cells throughout the body.
Do all flatworms show Cephalization?
Cephalization in the Animal Kingdom Flatworms (phylum Platyhelminthes) are the most primitive animals with bilateral symmetry. They also have a fairly advanced degree of cephalization, with sense organs (photosensory and chemosensory cells) and a brain concentrated at the anterior end.
What are two advantages to Cephalization?
There are multiple advantages to cephalization, including the development of a brain, the concentration of the sense organs at the anterior end of the body, and the close proximity of the mouth to the sense organs.
What is the importance of Cephalization?
Cephalization is important in that it allows for the organism to make quick movements. It also allows for the organism to have an axis of symmetry, further making quick movements possible as the organism can either find prey or avoid being prey. Cephalization allows for an organism to have a brain.
Do sea stars have Cephalization?
Echinoderms, or sea stars, also lack cephalization. Nearly all animals not falling into one of these categories exhibits some degree of cephalization.