The Hydrozoa is a class of Cnidaria. Most hydrozoans have a benthic, colonial polyp stage, which reproduces asexually by budding. Many have free swimming, sexually reproducing medusae (see Introduction to Ctenophores (and Cnidarian medusae)). Others have attached gonophores, which will produce eggs or sperm.
What are examples of scyphozoa?
Rhizostomae
SemaeostomeaeCrown jellyfishCoronamedusaeMawsonites
True jellyfishes/Lower classifications
What are characteristics of Hydrozoa?
Class Hydrozoa
- 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 unique about class Hydrozoa?
Like all cnidarians, hydrozoans have special ectodermal cells called cnidocytes, each containing a single intracellular structure called a cnida (aka nematocyst). Cnidae are unique to the Cnidaria. Each cnida, when triggered by a mechanical or chemical stimulus, shoots out a tiny hollow tube at high speed.
Is hydrozoa colonial or solitary?
Hydrozoa (hydrozoans, from ancient Greek ὕδωρ, hydōr, “water” and ζῷον, zōion, “animal”) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most living in salt water.
What is the life cycle of Hydrozoa?
The basic life cycle of hydrozoans comprises a succession of developmental stages: planula larva, hydroid and dioecious hydromedusa [2]. Sessile polyps produce medusae through asexual budding. A medusa is a mobile reproductive stage. After fertilisation a planula larva develops.
What is the difference between Hydrozoa and scyphozoa?
Differences between a Scyphozoan & Hydrozoan medusae? Schyphozoans – More ‘jelly & 4 oral arms. Hydrozoans – No oral arms. Have a velum ring & less jelly (fold up when preserved).
What is scyphozoa in biology?
The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or “true jellies”). The class name Scyphozoa comes from the Greek word skyphos (σκύφος), denoting a kind of drinking cup and alluding to the cup shape of the organism.
Why do you think class Hydrozoa is separated from other cnidarians?
Hydrozoans are unique from all other cnidarians in that their gonads are derived from epidermal tissue.
What is the common name for hydrozoa?
Integrated Taxonomic Information System – Report
| Common Name(s): | hydralike animals [English] |
| hydroids [English] | |
| hydrozoans [English] | |
| hydraires [French] | |
| hydrozoaires [French] |
What is hydrozoa scientific name?
Hydrozoa
Hydrozoans/Scientific names
What organisms are in hydrozoa?
Hydrozoa is a class within the phylum Cnidaria, which includes sea anemones, corals, and jellyfish. The vast majority are marine species, but freshwater hydrozoans are known, for example, Cordylophora lacustris and Craspedacusta sowerbyi.
