Animal Diversity I
BIOB 171
Introduction
• Domain Eukarya, Kingdom Animalia
• Heterotrophic – obtain food by ingesting
other organisms or their by-products
• Arose some 565 mya – Cambrian Explosion
Cambrian Explosion
• 565 to 525 million years ago
• Lasted for ~40 million years – very fast!
• 4 billion years, nothing but bacteria, plankton,
and algae existed.
• Most single celled or colonies.
• Then Cambrian Explosion…
• All major animal body plans appear in the
fossil record during this period.
Parazoa
Turn to page 181 in your lab manual and look at figure 1.
35 major groups – we’re looking at 9
Each group has a different body plan
Parazoa - asymmetrical
Eumetazoa
• All are multicellular animals
• Organisms in this group have
either radial or bilateral
symmetry
• It is a sub-kingdom that
includes everything except
sponges and a few other
random animals.
A little more detail…
• Domain Eukarya, Kingdom Animalia, Sub-kingdom
Eumetozoa
• Heterotrophic – obtain food by ingesting other organisms or
their by-products
• Lack cell walls
• Pass through a blastula stage 
• Arose approx. 620 - 550 mya
Protostomes vs. Deuterostomes
• Protostomes – blastopore becomes mouth
• Deuterostomes – blastopore becomes anus
Parazoa
Radialaria
Protostomes
Deuterostomes
Protostomes
• Two large groups:
– Lophotrochozoa – The name is based on the
trochophore larva found in within this group.
Includes annelids, molluscs, flatworms, and
rotifers
– Ecdysozoa – Animals in this group undergo
molting (ecdysis) or the shedding of an outer body
cover. Includes roundworms, nematodes,
arthropods (and others).
Porifera
Cnidaria
Platyhelminthes
Rotifera
Mollusca
Annelida
Basic Characteristics of Animals
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Pages 181 – 183
Read through and understand all 13
characteristics
Understand Figure 1, understanding the
differences between (a) and (b).
As you move through the lab looking at
organisms and doing the dissections, refer to
these characteristics.
Record your observations in your lab notebook
and fill out the table that I handed out. You will
be able to use this table on the final exam.
Phylum Porifera – Sponges
Exercise 1
• Unique body form that contains NO tissues and NO symmetry.
• Observe preserved specimens and slides
• Osculum – large opening to the body at one end, opposite end
attaches sponge to substrate
• Spicules – needle-like projections around the osculum and protruding
from the surface of the body – made of calcium carbonate – give
support and protection and prevent small animals from entering the
sponge’s internal cavity.
• Choanocyte or collar cell – unique to sponges, line the central cavity
and channels – each has a flagellum extending from its surface into
the water – their collective beating moves water through the sponge
body wall – small food particles are taken up and digested by collar
cells – cause water to move in through the channels and out the
osculum.
Phylum Cnidaria – Hydras (Hydra)
Exercise 2
• Two tissue types, no complex organs
• Includes: corals, jellies, sea anemones, and
Portuguese men-of-war.
• Most species are marine, few freshwater spp.
• Two body forms present in the life cycle:
– Umbrella-like, free-swimming stage
– Cylindrical, attached or stationary form – often grows
into colonies of individuals
• Observe live hydra in a depression slide.
• Also observe prepared slides
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Phylum Platyhelminthes
Planarians (Dugesia)
Exercise 3
Free-living flatworms
Bilaterally symmetrical, dorso-ventrally flattened
2 tissue types
Found under rocks, leaves, and debris in freshwater
ponds and creeks
• Move using muscles in their body and cilia on their
ventral side
• Feed by extending a long tubular pharynx of their
mouth, located on the ventral side of the body.
• Observe live Dugesia (feed liver) and prepared slides
Pharynx also
functions as the anus
Phylum Rotifera - Rotifers
• NOT IN LAB MANUAL
• Very small animals – most 0.1 –
0.5 mm in length
• Most common in freshwater,
though some salt water species
• Important part of freshwater
zooplankton, being a major food
source and many species
contributing to decomposition of
organic matter.
• Pharynx contains tiny, calcified,
jawlike structure called trophi
Phylum Annelida - Exercise 4
Clamworms (Nereis) and Earthworms (Lumbricus terrestris)
• Diverse group of animals that inhabit a variety
of environments.
• Sizes range from microscopic to several meters
in length
• Segmented “worms”
• Most species are marine, living free in the
open ocean or burrowing in ocean bottoms.
• Others live in freshwater or in soils
• Leeches are parasitic
Clamworms (Nereis)
Exercise 4: Lab Study A
• Dissect in pairs. Use lab manual and see handouts
on tables.
• Commonly found in mud flats and on the ocean
floor.
• Burrow in sediments during the day and emerge to
feed at night.
• Each segment bears fleshy outgrowths called
parapodia.
• At the end of each parapodium there are several
terminal bristles called setae
Earthworms (Lumbricus terrestris)
Exercise 4: Lab Study B
• Dissect in pairs. Use lab manual and handouts
on tables.
• You will also
look at prepared
slides
Phylum Mollusca
Exercise 5
• Thousands of
species with great
diversity in form
• Most species are
marine, but others
live in freshwater
or on land.
• Economically
important as a
food source for
humans.
Mollusk Characteristics:
1. A hard external shell for protection.
2. A thin structure called the mantle, which
secretes the shell
3. A visceral mass in which most organs are
located
4. A muscular foot used for locomotion.
Each pair will dissect a clam.
Last Notes
• Remember to record your observations in
your lab notebook and fill out the table I
handed out.
• Observed ALL specimens on display, they will
all be fair game on the practical unless I say
otherwise.
• Next week Animal Diversity II – read pgs. 201211