Chapter 32,33 : Animalia (2)

Question 1

Explain the nutrition and defense mechanisms of Cnidaria

Answer 1

Cnidarians are carnivores
* Tentacles with stinging cells (cnidocytes)
used in defense and capture of prey.
* Cnidocytes contain cnidae – capsule-like
structures capable of exploding outward
* Nematocysts (specialized cnidae) – contain a stinging thread that can penetrate the body wall of preys

Question 2

Which cnidaria alternates between 2 life forms?

Answer 2

Hydrozoans – most hydrozoans alternate between the polyp and medusa forms

Question 3

What are the characteristics of platyhelminthes?

Answer 3

Platyhelminthes - flatworms
* Habitat – marine, freshwater, and damp
terrestrial habitats
* Have thin bodies that are flattened
dorsoventrally(Bilateral, triploblastic, acoelomate)

• Life forms include:
  – free-living – microscopic & long worms
  – parasitic species e.g. tapeworm, fluke
  – they are usually hermaphrodites
• Organ grade level of organization
• Posses several distinct organs, organ
  systems and muscles

Question 4

What form does platyhelmintes come as? Explain their life cycle

Answer 4

Trematodes parasitize a wide range of hosts

• Most have complex life cycles with
  alternating sexual and asexual stages

Question 5

Explain the rotifera phylum.

Answer 5

Tiny animals 50 um – (500 um - 2 mm in sizes)
* Habitat – freshwater, marine, and damp soils.
* Multicellular organisms with specialized
organ systems.
* Alimentary canal with two digestive openings (mouth and anus).

Question 6

Describe the psudeocoloem and reproduction in rotifera

Answer 6

Pseudocoelom serves as hydrostatic skeleton.

• Reproduction by parthenogenesis or sexual

Question 7

What are the characteristics of lophophorates?

Answer 7

All have lophophore – a
crown of ciliated tentacles around
the mouth
* Mainly sessile with no
distinct head
* Presence of a true coelom
lined by mesoderm

Question 8

What are the characteristics of mollusca?

Answer 8

• Body plan – consist of 3 primary parts
• Muscular foot – locomotion, anchoring and digging.
• Visceral mass – contains most of the body
  organs
• Mantle – covers the visceral mass and secretes the shell.
• Most have separate sexes
• Many snails are hemaphrodites

Question 9

What are the characteristics of annelida?

Answer 9

1. True coelom and segmented body
2. Found in all habitats
3. Coelom partitioned by septa
4. Show metameric segmentation
   (repetition of body parts)
5. Peristaltic movement – coordination of
   longitudinal (inner) and circular (outer)
   muscles.
6. Complete digestive system

Question 10

What are the characteristics of nematoda?

Answer 10

• Habitat – freshwater, marine, moist soil, tissues of plants and tissues and body fluids of animals
• Pseudocoelomate
• A tough transparent cuticle
• Alimentary canal present but lack a circulatory system.
• Freeliving worms play important roles in
  decomposition and nutrient cycling

Question 11

What are the life forms of nematoda?

Answer 11

Life forms
* Parasites of plants and animals
* Humans are hosts to about 50 nematode species
* E.g. pinworm and hookworm
* Sources – eating raw or undercooked pork or other meat (wild game meat)

Question 12

What are the characteristics of Arthropoda?

Answer 12

Habitat – all habitats of the biosphere
* Most successful animal phyla

Body plan
* Covered by cuticle – exoskeleton made of
glycoproteins (polysaccharides)
* Rigid exoskeleton (chitin) offers protection
* Provides point of attachment for muscles
* Impermeable to water
* Segmented body – head, thorax and abdomen

Question 13

What are the characteristics of echinoderms?

Answer 13

Echinoderms
* Slow moving or sessile marine animals
* Internal and external parts radiate from the center
* Thin skin covers hard calcareous plates
* Tube feet for locomotion and feeding
* Sexual reproduction
* Separate males and females release
gamete into the water