28 Questions
What is the approximate number of living species of cnidarians?
10,000
Where are hydras typically found?
Freshwater habitats
What is the body symmetry of cnidarians?
Radial symmetry
What is the level of organization of cnidarian tissues?
Tissue level
What is the main characteristic of the polyp form of cnidarians?
Sessile and cylindrical
What is the characteristic of the medusa form of cnidarians?
Motile and bell-shaped
What is the common feature of all cnidarians?
Sac-like body with a single opening
What is the characteristic of the digestive system of cnidarians?
A single opening serving as both mouth and anus
What is the main function of nematocysts in coelenterates?
To capture and paralyze prey
What is the characteristic symmetry found in coelenterates?
Radial symmetry
What is the primary mode of respiration and excretion in coelenterates?
Simple diffusion
What is the function of the coelenteron in coelenterates?
To digest food
What is the characteristic feature of the skeletons of coelenterates?
Composed of calcium carbonate
What is the primary source of food for coelenterates?
Other animals that live symbiotically within them
What is the function of choanocytes in sponges?
To trap food particles and move water through the sponge
What is the name of the gelatinous material found between the pinacoderm and choanocytes in sponges?
Mesohyl
Which of the following is a characteristic of the subkingdom Parazoa?
Sessile, attached to the substrate
What is the function of the osculum in sponges?
To release waste and excess water from the sponge
What is the name of the inner layer of cells in sponges that lines the atrium?
Choanocytes
What is the subkingdom classification of the phylum Coelenterata?
Metazoa
What is the name of the phylum that includes sponges?
Porifera
Which class of Coelenterata only has the hydroid form during their life cycle?
Actinozoa
What is the main characteristic that distinguishes Metazoa from Parazoa?
Body composed of cells differentiated into tissues and organs
What is the genus of the species Hydra viridis?
Hydra
What is the name of the cells in sponges that can phagocytize food particles?
Archaeocytes
What is the body structure of Hydra characterized by?
Small and may occur as solitary or colonial
What is unique about the body composition of jellyfish?
Their body is almost totally made of water
What is absent in jellyfish?
All of the above
Study Notes
Subkingdom: Parazoa
- Phylum: Porifera
- Example: Sponge
- Characteristics:
- Mostly marine, but some freshwater inhabitants
- Sessile; permanently attached to substrate
- Filter feeding
- Body wall composed of:
- Pinacoderm (outer layer of flattened cells)
- Choanocytes (inner lining of flagellated cells)
- Mesohyl (gelatinous material between pinacoderm and choanocytes)
- Three types of body structure: Ascon, Sycon, and Leucon
Kingdom: Animalia
Subkingdom: Metazoa
- Characteristics:
- Body composed of cells differentiated into tissues and organs
- Digestive cavity lined with specialized cells
- Divided into two groups: Diploblastica and Triploblastica
Diploblastica
- Characteristics:
- Two layers: ectoderm and endoderm
- Non-cellular layer (mesogloea) between ectoderm and endoderm
- Coelom absent
Triploblastica
- Characteristics:
- Three layers: ectoderm, mesoderm, and endoderm
- Cellular layer (mesoderm) between ectoderm and endoderm
- Coelom present
Phylum: Cnidaria (Coelenterata)
- Characteristics:
- Radial symmetry
- Tissue level of organization
- Over 10,000 living species
- Both marine and freshwater habitats
- Two general body forms: Polyp and Medusa
- Body plan: Sac with a central digestive compartment
- Single opening serving as both mouth and anus
- Ring of tentacles on oral surface
General Characters
- Multicellular organisms with tissue grade of organization
- Diploblastic, with two layers of cells: ectoderm and endoderm
- Single opening in the body for food intake and waste expulsion
- Radial symmetry
- Digestion occurs in the body cavity (coelenteron)
- Can live in marine or freshwater habitats
- Can be solitary or colonial
- Each individual is a zooid
- Two morphological forms: Polyps and Medusa
- Most are carnivorous, with some exceptions
Phylum: Coelenterata (Cnidaria)
Class: Hydrozoa
- Characteristics:
- Show asexual hydroid and sexual medusoid forms during their life cycle
- Examples: Hydra, Obelia
Class: Actinozoa (Anthozoa)
- Characteristics:
- Only have the hydroid form during their life cycle
- Example: Alcyonium
Genus: Hydra
Species: viridis
- Example: Hydra viridis
Body Structure of Hydra
- Not specified
Characteristics of Moon Jelly
- Not specified
Obelia Hydroid
- Characteristics:
- Prominent medusa and polyp forms
Jellyfish
- Characteristics:
- No eyes, nose, brain, or heart
- Body is mostly made of water and is soft
- No bones or spine
- Invertebrate animals
Learn about the characteristics and features of the Subkingdom Parazoa, specifically the Phylum Porifera, including their habitats, body structure, and feeding methods.
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