Podcast
Questions and Answers
What type of cells does the ectoderm layer consist of?
What type of cells does the ectoderm layer consist of?
What happens when the longitudinal muscle fibres of the musculo-epithelial cells contract equally on all sides?
What happens when the longitudinal muscle fibres of the musculo-epithelial cells contract equally on all sides?
What is unique about the nerve cells of Hydra?
What is unique about the nerve cells of Hydra?
How does Hydra digest its food?
How does Hydra digest its food?
Signup and view all the answers
What is the primary storage product of excess food in Hydra?
What is the primary storage product of excess food in Hydra?
Signup and view all the answers
How do Hydra typically move from one place to another?
How do Hydra typically move from one place to another?
Signup and view all the answers
What is the function of the glandular cells in Hydra?
What is the function of the glandular cells in Hydra?
Signup and view all the answers
What happens to indigestible food in Hydra?
What happens to indigestible food in Hydra?
Signup and view all the answers
What is the shape of the body of Hydra?
What is the shape of the body of Hydra?
Signup and view all the answers
What is the function of the penetrant type of nematocysts in Hydra?
What is the function of the penetrant type of nematocysts in Hydra?
Signup and view all the answers
How many types of nematocysts are recognized in Hydra?
How many types of nematocysts are recognized in Hydra?
Signup and view all the answers
What is the location of the ovary in Hydra?
What is the location of the ovary in Hydra?
Signup and view all the answers
What is the name of the cavity that extends into the tentacles in Hydra?
What is the name of the cavity that extends into the tentacles in Hydra?
Signup and view all the answers
What is the function of the volvents type of nematocysts in Hydra?
What is the function of the volvents type of nematocysts in Hydra?
Signup and view all the answers
What is the composition of the body wall of Hydra?
What is the composition of the body wall of Hydra?
Signup and view all the answers
What is the function of the glutinants type of nematocysts in Hydra?
What is the function of the glutinants type of nematocysts in Hydra?
Signup and view all the answers
Study Notes
Body Structure
- Hydra is a freshwater solitary animal with a cylindrical body (2-20 mm in length)
- It has a basal disc for attachment and a free oral cone (hypostome) bearing the mouth
- The mouth is situated on a conical hypostome encircled by 6-10 hollow filiform tentacles in one cycle
- The tentacles are provided with nematocysts
Reproductive System
- Gonads appear as buds on the side of the body stalk
- Several testes arise on the sides of the upper third of the body near the oral end
- One ovary is present near the basal disc
- Lateral buds may be present by asexual reproduction
Nematocysts
- There are four kinds of nematocysts in Hydra: penetrants, volvents, small stereoline glutinants, and large streptoline glutinants
- Each type of nematocyst has a specific function: defense, catching prey, and food collection
- Nematocysts respond only to mechanical stimuli
Body Wall
- The body wall of Hydra viridis is diploblastic, consisting of an outer ectoderm (epidermis) and inner endoderm
- The ectoderm and endoderm are separated by a thin structureless jelly-like mesogloea
- The body wall encloses a digestive cavity (coelenteron) that extends into the tentacles
Ectoderm and Endoderm
- Ectoderm cells are musculo-epithelial, interstitial, nematoblast, sensory, nerve, mucous cells, and germ cells
- Endoderm cells are musculo-nutritive, interstitial, sensory, nerve (less developed cells), glandular or secretory cells, and few mucous cells around the mouth
- Musculo-epithelial cells have longitudinal muscle fibres that contract to shorten or bend the body
- Musculo-nutritive cells have circular muscle fibres that contract to narrow and elongate the body
Nutrition and Digestion
- Hydra is carnivorous, feeding on freshwater microorganisms, small crustaceans, and insect larvae
- Food is digested extracellularly by secreting proteolytic enzymes from the glandular cells of the endodermal layer
- Nutritive muscle cells engulf small fragments of food, forming food vacuoles and undergoing intracellular digestion
- The products of digestion are absorbed by the nutritive cells and circulated by cellular diffusion
Respiration and Excretion
- Respiration and excretion take place by diffusion
Locomotion
- Hydra is essentially sessile and lives attached to the substratum by a sticky secretion
- It can move from one place to another by gliding, walking, somersaulting, and floating
- Walking is the most common method of locomotion, using the adhesive threads of the small glutinant nematocysts
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the physical characteristics and features of Hydra, a freshwater solitary animal. Learn about its body structure, tentacles, and reproductive organs. Test your knowledge of Hydra's biology!
