Bi 101 (Fall 2006) Animal Diversity I: Invertebrates Dr. Dutton

What Are the Key Features of Animals?

These characteristics collectively define an animal:

(1) they have _________________________ bodies;

(2) they obtain _________________________ by eating the bodies of other organisms (i.e., they are heterotrophic);

(3) they typically reproduce _________________________;

(4) their cells lack cell _________________________;

(5) they are _________________________ (i.e., they can move around); and

(6) most respond rapidly to _________________________ stimulation

Which Anatomical Features Mark Branch Points on the Animal Evolutionary Tree?

The early fossil record is very sparse and does not reveal the sequence in which animal phyla arose

Therefore, evidence for the evolutionary history of animals has primarily come from:

_________________________,

_________________________ development, and

_________________________ sequence comparisons

Certain features mark major branching points on the animal evolutionary tree

Figure 22-1

What Are the Major Evolutionary Trends in Animals?

Evolutionarily, animals have increased in complexity in many ways

They have increased cellular organization and specialization: cells are the basic unit of

life, _________________________ are groups of similar cells,

_________________________ are groups of different tissues, and

_________________________ _________________________ are groups of different organs

Animals have become increasingly symmetrical

Some animals, such as sponges, have no symmetry (asymmetrical) while other animals are symmetrical

Symmetrical animals can be divided into two groups

_________________________ Symmetry (wheel-like symmetry)

includes animals such as cniderians, and some adult echinoderms

_________________________ symmetry (right-left or dorsal-ventral mirror images) is found in more complex animals and larval echinoderms

Figure 22-2

Also, there is an increase in _________________________ (tissue) layers:

Sponges have no true tissues;

Radially symmetrical animals have two germ layers:

The inner _________________________ lines most hollow organs

The outer _________________________, an epithelial tissue covers the body and lines the inner cavities, plus the nervous system cells;

Bilaterally symmetrical animals have a third layer in the middle, the

_________________________, which forms muscular, circulatory, and skeletal systems

_________________________ (concentration of sensory organs and brain in the head) has accompanied by the development of bilateral symmetry

Radial animals tend to be _________________________ and have no front or back ends

Bilateral animals (flatworms and higher forms) move forward and have concentrations of

sensory organs in the _________________________ (front or head) end

The other end is the _________________________ end and may feature a tail

Another evolutionary trend has been in the development of the body cavity between the digestive tube or gut and the outer body wall

Such body cavities free the gut from being attached to the body wall so it can digest food more effectively, and create space for internal organs

Cnidarians and flatworms lack body cavities (_________________________),

roundworms have a _________________________ (body cavity partially lined with mesoderm tissues), and annelids and higher groups have a true

_________________________ (body cavity totally lined with mesoderm tissue)

Figure 22-3)

Coeloms develop in one of two general ways

In _________________________ animals (annelids, arthropods, and mollusks), the coelom develops in spaces between the gut and body wall

In _________________________ animals (echinoderms and chordates), the coelom develops from outgrowths of the gut

What Are the Major Animal Phyla?

There are two major categories of animals.

_________________________, animals without backbones, are the earliest animals comprising 97% of animals today

_________________________, animals with backbones (the fish, amphibians, reptiles, birds, and mammals) all are in the phylum …

_________________________ (Figure 22-1)

Important Characteristics for Distinguishing different Animals Groups

KNOW Table 22-1!

The Sponges: Phylum Porifera

Sponges lack true tissues and organs. The sponge body is perforated with numerous tiny pores

Three major cell types are present:

(1) _________________________ cells on the body surface, including pore cells;

(2) _________________________ cells with flagella to control water flow; and

(3) _________________________ cells to digest and distribute nutrients and make

reproductive cells and spines called _________________________

They have an internal skeleton make of calcium carbonate, silica, or protein

They may reproduce asexually by budding or sexually through fusion of sperm and egg (Figure 22-4)

The Hydra, Anemones, and Jellyfish: Phylum Cnidaria

Cnidarians are radially symmetrical, have two germ layers (ectoderm and endoderm)

with jellylike _________________________ between, have true tissues and a

_________________________ _________________________ to control contractile tissue and feeding, but lack organs and brains

The two body plans are the sessile tubular _________________________, usually

attached to rocks and possessing _________________________ to attack and seize

prey, and the mobile swimming _________________________ ("jellyfish"), with trailing

tentacles armed with _________________________ cells that eject poisonous or sticky

darts to capture prey

The prey is moved into the digestive sac (_________________________

_________________________) with one opening, the mouth/anus

Cnidarians can reproduce _________________________ (budding off replicas) and

_________________________

One group, the corals, with limestone shells, form reefs that are the basis for a diverse ecosystem (Figures 22-7 & 22-8)

The Flatworms: Phylum Platyhelminthes

Flatworms have bilateral symmetry, a gastrovascular (GV) digestive cavity,

cephalization with _________________________ (clusters of nerve cells) in the

anterior brain, and _________________________ _________________________.

Flatworms lack circulatory and respiratory systems, relying on diffusion to move molecules

Flatworms reproduce asexually and sexually; most are _________________________ (possess both male and female sex organs)

Some parasitic flatworms are intestinal tapeworms (ingested as encapsulated

_________________________) and liver and blood flukes (Figures 22-9 & 22-10)

The Segmented Worms: Phylum Annelida

Annelid (9000 species) bodies consist of a series of repeating

_________________________, each with nerve ganglia excretory structures

(_________________________), and muscles and a true coelom acting as a

_________________________ skeleton. They have a _________________________

_________________________ _________________________ (blood is confined to the heart and blood vessels)

The digestive system of earthworms consists of mouth, pharynx, esophagus, crop, gizzard, intestine, and anus

Segmented worms include oligochaetes (e.g., earthworms), polychaetes, and leeches (Figure 22-11)

The Snails, Clams, and Squid: Phylum Mollusca

Molluscs have a moist, muscular body with a hydrostatic skeleton, an open circulatory

system, the _________________________ (except in the cephalopods), and a

_________________________ (body wall extension that forms a gill chamber)

Some have a calcium carbonate shell secreted by the mantle

Three important classes are the:

1. Gastropods (snails and slugs) have a muscular foot and a rasping radula used to scrape algae from rock for food

2. Bivalves (scallops, mussels, clams, and oysters are bivalve mollusks) with

_________________________ _________________________ connected by a flexible hinge

They are filter feeders, using gills for respiration and feeding

3. Cephalopoda (octopuses, squids, nautiluses, and cuttlefish) are cephalopod mollusks , mostly marine predators

The foot has evolved into _________________________ with suction discs, and they move by jet propulsion caused by forceful expulsion of water from the mantle cavity

Figures 22-13, 22-15, 22-16

The Insects, Arachnids, and Crustaceans: Phylum Arthropoda

Arthropods (> 1,000,000 species) are the most successful group of animals on Earth due to these adaptations:

_________________________ _________________________ with jointed appendages;

_________________________;

efficient gas exchange mechanisms including gills (in crustaceans),

_________________________ (insects), or _________________________ lungs (spiders);

open circulatory systems (blood flows through vessels and enclosed body cavities called hemocoels); and

well-developed sensory and nervous systems, including compound

_________________________

The exoskeleton periodically must be shed (_________________________) and replaced with a larger one

Insects are the most diverse and abundant arthropods (850,000 species, class Insecta), with three pairs of legs and two pairs of wings

_________________________ insects undergo complete

_________________________: from the egg to the _________________________

(adapted for feeding) to the _________________________ (non-feeding form in which physical changes occur) to the adult adapted for reproduction (Figure 22-19)

Spiders, scorpions, ticks, and mites are arachnids (class Arachnida) with four pairs of

legs and _________________________ eyes

Most are carnivorous predators

Crabs, shrimp, crayfish, lobsters, and barnacles are crustaceans (class Crustacea), the only primarily aquatic arthropods

Crustaceans have two pairs of _________________________ and many other appendages, compound eyes, and gills

The Roundworms: Phylum Nematoda

Nematodes have a tubular, one-way digestive tract (mouth, intestine & anus), a fluid-

filled _________________________ that acts as a hydrostatic skeleton, and a head with a brain

They lack circulatory and respiratory systems, relying on diffusion to move molecules

Most reproduce _________________________ and have separate male and female sexes

Billions thrive in each acre of topsoil

Parasites include trichinella, hookworm, and heartworm (Figure 22-26)

The Sea Stars, Sea Urchins, Sand Dollars, and Sea Cucumbers: Phylum Echinodermata

The echinoderms have:

free swimming embryos with _________________________ symmetry, but the adults

have five-parted _________________________ symmetry, lack a head, have an

internal _________________________ of calcium carbonate plates, and move slowly by using tube feet (rows of suction cups) which are part of the water vascular system (water enters through a sieve plate, passes through a ring canal and into radial canals, each of which has many tube feet each with a muscular

_________________________ or squeeze bulb)

They have no circulatory system

Sea stars can regenerate lost parts (Figure 22-28)

Summary: Major Points

This chapter has covered…

A LOT!

Several major Phyla of animals including the invertebrates (sponges, cnidarians, flat-, round-, and segmented worms, arthropods, molluscs, and echinoderms)

KNOW Table 22-1 - it is a summary of the major characteristics of each phylum of animals discussed in this chapter