What symmetry is hydrozoa?
They are often formed by budding from polyps, and are usually solitary free-swimming organisms. They are similar in structure to an inverted polyp, radially symmetric, and often have four-fold symmetry.
What type of body symmetry allows for cephalization?
bilateral symmetry
Cephalized organisms display bilateral symmetry. Sense organs or tissues are concentrated on or near the head, which is at the front of the animal as it moves forward.
Are hydrozoa bilaterally symmetrical?
In Medusozoa, the bilateral symmetry is replaced by radial symmetry, but some hydrozoans (for example, Corymorphidae) demonstrate bilateral symmetry.
What is the relationship between cephalization and symmetry?
Cephalization is an evolutionary trend in which, over many generations, the mouth, sense organs, and nerve ganglia become concentrated at the front end of an animal, producing a head region. This is associated with movement and bilateral symmetry, such that the animal has a definite head end.
What are the characteristics of Hydrozoa?
Main attributes:
- Internal space for digestion is the gastrovascular cavity.
- Gastrovascular cavity has one opening, the mouth.
- Exoskeleton of chitin.
- Are almoust entirely marine and predators.
- Sexual reproduction produces the planula larvae.
- Two body forms, a polyp and medusea.
- Presence of stinging cells called Cnidocytes.
What is the order of Hydrozoa?
Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria….Hydrozoa.
| Hydrozoa Temporal range: | |
|---|---|
| Subphylum: | Medusozoa |
| Class: | Hydrozoa Owen, 1743 |
| Subclasses and orders | |
| Hydroidolina Anthoathecata Leptothecata Siphonophorae Trachylinae Actinulida Limnomedusae Narcomedusae Tatalidoae |
Which phylum has cephalization?
Phylum Platyhelminthes
Members of the Phylum Platyhelminthes (especially true of the planarians, Class Turbellaria) are organized with brain and sense organs at the front of the animal. This is called cephalization. In animals with cephalization, the sense organs come in contact with the environment first.
What are the 3 types of body symmetry?
At a very basic level of classification, true animals can be largely divided into three groups based on the type of symmetry of their body plan: radially symmetrical, bilaterally symmetrical, and asymmetrical.
Do cnidarians have Cephalization?
Cnidarians are radially symmetrical (i.e., similar parts are arranged symmetrically around a central axis). They lack cephalization (concentration of sensory organs in a head), their bodies have two cell layers rather than the three of so-called higher animals, and the saclike coelenteron has one opening (the mouth).
What type of symmetry do nematodes have?
Like the flatworms, nematodes are bilaterally symmetrical.
How are body symmetry and cephalization related quizlet?
Most animals that exhibit bilateral symmetry have their sense organs and nerve cells concentrated at the front of their bodies. This characteristic is called cephalization, which forms the head of an animal. If an animal exhibits body symmetry and cephalization, it can detect stimuli in their environment more quickly.
Do bilaterally symmetrical animals have cephalization?
Nervous Systems of Animals with Bilateral Symmetry Exhibit Centralization and Cephalization.
How does cephalization occur in bilaterally symmetric body plans?
Bilateral plans have only one plane of symmetry, which results in a body that has a front end, such as a head, and a back end, such as a tail. Cephalization often, but not always, occurs with the bilaterally symmetric body plan. Primitive organisms, such as sea anemones, have a diffuse nervous system in which neurons are spread throughout the body.
What is Hydrozoa?
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south. an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes). Bouillon, J., C. Gravili, F. Pagès, J. Gili, F. Boero. 2006. An Introduction to Hydrozoa.
What is the difference between hydrozoans and scyphozoans?
Hydrozoans have a sexual medusa stage and a nonsexual polyp stage, whereas scyphozoans have a shortened asexual polyp stage. Hydrozoans have velum at the medusa that aids in propulsion, but scyphozoan polyps lack this velum.
What is cephalization in vertebrates?
Cephalization in vertebrates, the group that includes mammals, birds, and fishes, has been studied extensively. The heads of vertebrates are complex structures, with distinct sense organs; a large, multi-lobed brain; jaws, often with teeth; and a tongue.