BY 124 SI worksheet 8

Which of the following statements is not true regarding cnidarians?

  1. An alternation of medusa and polyp stage is common in clade hydrozoa
  2. They use a rung of tentacles armed with stinging cells to capture prey

c.  They include corals, jellies, sponges, and sea anemones

  1. They have a nerve net that coordinates contraction of microfilaments for movement
  2. They have a gastrovascular cavity

Which of the following combinations of phylum and characteristics is incorrect?

  1. Brachiopoda – lophophore, stalked, marine animals with hinged shells
  2. Rotifera – crown of cilia, microscopic animals, (some) parthenogenesis

c.  Nematoda – gastrovascular cavity, tough cuticle, ubiquitous

  1. Annelida – segmentation, closed circulatory system, hydrostatic skeleton
  2. Echinodermata – radial anatomy in adults, endoskeleton, water vascular system.

Torsion

a.  Is embryonic rotation of the visceral mass that results in a U-shaped digestive tract in gastropods

  1. Is part of the process of molting in the incomplete metamorphosis of some insects.
  2. Is responsible for the spiral growth of bivalve shells
  3. Describes the thrashing movement of nematodes
  4. Is a stage in the complete metamorphosis of some insects.

Which of the following structures does not function in suspension feeding?

  1. The lophophore of Ectoprocts

b.  The radula of snails

  1. The Choanocytes of sponges
  2. The mucus-coated gills of clams
  3. The crown of cilia in rotifers

The proglottids of a tapeworm contain an elaborate _____ system.

  1. Digestive

b.  Reproductive

  1. Circulatory
  2. Attachment
  3. Sensory

Some species of rotifers undergo parthenogenesis, which means that _____.

a.  the species consists of only females that produce more females from unfertilized eggs

b.  each individual functions as both male and female in sexual reproduction by producing sperm and eggs

c.  their larval stage of development looks completely different from the adult stage

d.  during development of adult forms, some of the organs that were bilateral are reduced in size or are lost on one side of the body

e.  they shed their exoskeleton as they grow

The majority of animal species are _____.

  1. Acoelomates
  2. Nematodes
  3. Vertebrates

d.  Insects

  1. Marine

What is the difference between a closed and open circulatory system? Where might you find each one?

Vertebrates, and a few invertebrates, have a closed circulatory system. Closed circulatory systems have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities.

The open circulatory system is common to molluscs and arthropods. Open circulatory systems (evolved in crustaceans, insects, mollusks and other invertebrates) pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells. Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood.

Describe the purposes of the following structures in molluscs:

a)  Foot – locomotion/movement

b)  Visceral mass – holds the internal organs of the mollusk

c)  Mantle – secretes a shell. If the mantle extends beyond the visceral mass a mantle cavity can house the gills, or excratory pores.

d)  Radula – apparatus for scraping up food or drilling holes in other organisms for feeding.

How are leeches able to prevent blood from coagulating when drawing it from the host?

They secrete the chemical hirudin which acts as an anticoagulant. It prevents the blood from coagulating so that the leech can continually feed. They also secrete a chemical that numbs the feeding site so the host is less likely to notice the leech.

In the absence of a brain, how are cnidarians able to coordinate bodily functions?

Cnidarians use what is called a nerve net. It is not a brain and does not display cephalization. They are spread throughout the organism and allow it to respond to its environment but not much else

True or false: the body of a Chiton is segmented

False. The shell is segmented but the body is not

What are the two ways that planarians are able to reproduce?

Planarians can reproduce asexually through fission (separate then regenerate) or sexually (hermaphrodites)