Chapter 7 Invertebrates Flashcards
radial symmetry
organisms have several ways in which they can be sectioned in half, and still have two equal halves, each being a mirror image of the other.
Bilateral Symmetry
There is only one way in which the animal can be divided in half to make two equal halves with each half being a mirror image of the other
Asymmetric
In these organisms, there is no way in which it can be divided into two equal halves which are mirror images. They have an irregular shape.
Monecious
one individual has both male and female sex organs (“one-house”)
Dioecious
two separate sexes. Each individual is either a male or a female (“two houses”)
Asexual
new individuals develop without gametes; either by “budding” or by “regeneration.”
Oral
mouth end
aboral
end opposite of the mouth
distal (terminal)
end of appendage opposite to where it is attached.
basal (proximal)
end of appendage to where it is attached
anterior
front end (i.e. the direction it moves)
dorsal
back
lateral
side
ventral
belly
posterior
rear end
cross section
cut upon a segmented worm vertically and it is the middle portion.
median longitudinal cross section
cut a worm horizontally into long sections
Phylum: Cnidaria (polyp - sea anemone, medusa - jellyfish, and coral).
What are the three characteristics?
- gastrovascular cavity
- tentacles
- stinging cells
3 Classes of sponges
- Bath sponge: contain “spongin” which are elastic fibers.
- Calcareous sponges: contain calcium carbonate making them hard like tiny needles.
- Glass sponges: contain silica (glass-like) spicules.
Phylum: Platyhelminthes
What are the three classes?
- Free-living (i.e. planarians)
- Tapeworms - intestinal parasite in humans or other vertebrates.
- have segments
- each segment has both female and male sex organs
- has scolex, suckers, and spines which allows it to attach to the wall of the hosts intestines. - Flukes
- look similar to freeliving flat worms
- have complex life cycle
Phylum: Nematoda (Ascaris, Hookworm, Pinworm)
What are some characteristics?
- contain roundworms
- they have no circulatory system
- they have no hair
- have a flat, non-muscular digestive tract
Why do Ascaris produce so many eggs?
Because the life cycle is complex so by producing many eggs it ensures at least 1 will survive.
Phylum: Annelida
-bodies composed of many, similar, ring-like segments; thus, they are commonly called the segmented worms.
-usually have hairs, or at least a few short bristles.
-contain a muscular digestive tract
-contain circulatory system with blood
Ex: Earthwords (Class: Oligochaeta), Leeches (Class: Hirudinea).
Mollusca
snails; bivalves; chitons; and cephalopods
- soft body and hard shell
- muscular foot and mantle
Echinodermata
starfish; sea urchins; brittle stars; sand dollars
-tube feet; spiny skin; pentra-radial symmetry; water-vascular system
