Biology Chapter 23
Describe the body of a flatworm. Include the names for the sides or directions of the body surfaces.
Flatworms are mostly small, leaflike or ribbonlike with a distinct head, or anterior end, and tail, or posterior end. It also has a back (dorsal) surface, a bottom (ventral) surface, and two side (lateral) surfaces.
Define gastrovascular cavity. What is the function of circulating fluid within this cavity? What happens to undigested food?
Gastrovascular cavity: a digestic sac Circulating fluids: transport digested food to, and wastes from, the cells lining the cavity. Undigested food & wastes exit back through the mouth.
Where are sense organs located on most bilaterally symmetrical animals?
In most bilateral animals, the eyes and other sense organs are located up front, on the head.
How does a cnidarian obtain food?
Its tentacles maneuver the food into its mouth, located at the center of the ring of tentacles.
To what phylum do flatworms belong?
Platyhelminthes
What 2 characteristics do all cnidarians share? Describe or define each.
Radial symmetry and tentacles with stinging cells. radial symmetry- a body plan in which an organism can be divided into equal parts around a central axis. Stinging cells (cnidocytes) are especially abundant along the tentacles. A stinging capsule is located within each cnidocyte.
To which phylum do sponges belong
Sponges belong to phylum Porifera
What defense mechanisms do sponges possess?
Sponges have chemical defenses including toxins that keep predators from eating the sponges and powerful antibiotics that fight bacterial infections.
What is the flexible material found in the skeletons of commercial sponges?
Spongin
What is the difference between a blastula and a gastrula? Which develops first
The blastula consists of a single layer of cells surrounding a hollow cavity. The gastrula has both an outer and an inner cell layer. The blastula develops first.
Describe the body of a typical sponge
The body of most sponges consists of two layers of cells separated by a jelly-like material. The outer layer of cells protects the interior of the sponge and also has many pores (holes) through which water can enter the sponge. The inner layer of cells lines the central cavity of the sponge.
Name the 3 types of tissue that flatworms have and the structures formed by each.
The ectoderm, mesoderm, and endoderm. The ectoderm develops into the body covering, the mesoderm develops into an internal tissue-filled region, and the endoderm develops into the digestive sac.
What 3 methods of reproduction are found in sponges?
a) Budding (a form of asexual reproduction in which new sponges develop from an outgrowth of the parent), b) Small fragments of a sponge body can grow into an entire new sponge, c) Sponges can also reproduce sexually.
Define bilateral symmetry.
bilateral symmetry: body plan in which an animal can be divided into two equal sides
What disease does Schistosoma cause?
blood fluke disease
What characteristics differentiate vertebrates from invertebrates? Define vertebra
invertebrates, animals without backbones. Vertebrates, animals with backbones, vertebra: segment of the backbone; encloses and protects the nerve cord
Define larva. What happens to larvae during metamorphosis
larva: immature form of an animal that looks different from the adult form During metamorphosis, The larva undergoes a change of body form, and becomes an adult.
Throughout most of their lives, sponges are sessile. Define sessile.
sessile: anchored in place
Describe feeding in a sponge
The flagella of collar cells generate water currents that move water through the sponge's pores and into the central cavity. As water flows through the sponge's body, it is filtered for food particles (mostly bacteria) in the water. Collar cells trap the food particles in mucus. Amoebocytes then engulf the particles and transport them to other cells. The water drawn in through the pores exits through the large opening at one end of the sponge.
Differentiate between a polyp and a medusa. In what different ways do cnidarians exhibit these body forms?
The polyp is a cylindrical body with tentacles radiating from one end. The medusa is an umbrella-shaped form with fringes of tentacles around the lower edge. Some cnidarian life cycles include both a medusa stage and a polyp stage. Others exist only as medusas. Still others such as hydras and sea anemones exist only as polyps.
What features do cnidarians possess that sponges lack?
The presence of a gastrula stage during embryonic development. Additionally, cnidarians have some basic tissues.
Does Taenia have a digestive system? How does it obtain its food?
The tapeworm itself has no digestive or circulatory system. Surrounded by partially digested food in their hosts' intestines, tapeworms absorb nutrients across their body surface.
What are the 4 characteristics of animals
eukaryotic lack cell walls multicellular heterotrophs
