Homework Questions--emailed to
valenciabiologyhw@gmail.com
1.
Compare developmental differences between protostomes and deuterostomes includng
a.
plane of cleavage
b.
determination
c.
fate of balstopore
d.
coelom
formation
2.
Describe the anatomy and generalized life cycle of a tapeworm
3.
List characteristics of arthropods (Phylum Arthropoda)
that distinguish them from other animal phyla
4.
Distinguish among the following arthropod classes and give an example of each
0. Arachnida
1. Crustacea
2. Diplopoda
3. Chilopoda
4. Insecta
5 Distingush between incomplete and complete metamorphosis
6 ) Which of the following factors, when used to label the horizontal axis
of the previous graph, would account most directly for the shape of the plot?
Animal 2
Lecture Notes
Overview: Life Without a Backbone
Invertebrates
Are animals that lack a backbone
Account for 95% of known animal species
A review of animal phylogeny
Exploring invertebrate diversity
Sponges are sessile and have a porous body and choanocytes
Sponges, phylum Porifera
Live in both fresh and marine waters
Lack true tissues and organs
Sponges are suspension feeders
Capturing food particles suspended in the water that passes through their body
Choanocytes, flagellated collar cells
Generate a water current through the sponge and ingest suspended food
Most sponges are hermaphrodites
Meaning that each individual functions as both male and female
Cnidarians have radial symmetry, a gastrovascular cavity, and cnidocytes
All animals except sponges
Belong to the clade Eumetazoa, the animals with true tissues
Phylum Cnidaria
Is one of the oldest groups in this clade
There are two variations on this body plan
The sessile polyp and the floating medusa
Cnidarians are carnivores
That use tentacles to capture prey
The tentacles are armed with cnidocytes
Unique cells that function in defense and the capture of prey
The phylum Cnidaria is divided into four major classes
Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa
Hydrozoans
Most hydrozoans
Alternate between polyp and medusa forms
Scyphozoans
In the class Scyphozoa
Jellies (medusae) are the prevalent form of the life cycle
Cubozoans
In the class Cubozoa, which includes box jellies and sea wasps
The medusa is box-shaped and has complex eyes
Anthozoans
Class Anthozoa includes the corals and sea anemones
Which occur only as polyps
: Most animals have bilateral symmetry
The vast majority of animal species belong to the clade Bilateria
Which consists of animals with bilateral symmetry and triploblastic
development
Flatworms
Members of phylum Platyhelminthes
Live in marine, freshwater, and damp terrestrial habitats
Are flattened dorsoventrally and have a gastrovascular cavity
Although flatworms undergo triploblastic development
They are acoelomates
Flatworms are divided into four classes
Turbellarian
Turbellarians
Are nearly all free-living and mostly marine
The best-known turbellarians, commonly called planarians
Have light-sensitive eyespots and centralized nerve nets
Monogeneans and Trematode
Monogeneans and trematodes
Live as parasites in or on other animals
Parasitize a wide range of hosts
Trematodes that parasitize humans
Spend part of their lives in snail hosts
Most monogeneans
Are parasites of fish
Tapeworm
Tapeworms
Are also parasitic and lack a digestive system
Rotifers
Rotifers, phylum Rotifera
Are tiny animals that inhabit fresh water, the ocean, and damp soil
Rotifers are smaller than many protists
But are truly multicellular and have specialized organ systems
Rotifers have an alimentary canal
A digestive tube with a separate mouth and anus that lies within a
fluid-filled pseudocoelom
Rotifers reproduce by parthenogenesis
In which females produce more females from unfertilized eggs
Lophophorates: Ectoprocts, Phoronids, and Brachiopods
Lophophorates have a lophophore
A horseshoe-shaped, suspension-feeding organ bearing ciliated tentacles
Ectoprocts
Are colonial animals that superficially resemble plants
Phoronids
Are tube-dwelling marine worms ranging from 1 mm to 50 cm in length
Brachiopods superficially resemble clams and other hinge-shelled molluscs
But the two halves of the shell are dorsal and ventral rather than lateral, as
in clams
Nemerteans
Members of phylum Nemertea
Are commonly called proboscis worms or ribbon worms
The nemerteans unique proboscis
Is used for defense and prey capture
Is extended by a fluid-filled sac
Nemerteans also have a closed circulatory system
In which the blood is contained in vessels distinct from fluid in the body
cavity
Molluscs have a muscular foot, a visceral mass, and a mantle
Phylum Mollusca
Includes snails and slugs, oysters and clams, and octopuses and squids
Most molluscs are marine
Though some inhabit fresh water and some are terrestrial
Molluscs are soft-bodied animals
But most are protected by a hard shell
All molluscs have a similar body plan with three main parts
A muscular foot
A visceral mass
A mantle
Most molluscs have separate sexes
With gonads located in the visceral mass
The life cycle of many molluscs
Includes a ciliated larval stage called a trochophore
There are four major classes of molluscs
Chitons
Class Polyplacophora is composed of the chitons
Oval-shaped marine animals encased in an armor of eight dorsal plates
Gastropods
About three-quarters of all living species of molluscs
Belong to class Gastropoda
Most gastropods
Are marine, but there are also many freshwater and terrestrial species
Possess a single, spiraled shell
Slugs lack a shell
Or have a reduced shell
The most distinctive characteristic of this class
Is a developmental process known as torsion, which causes the animals anus
and mantle to end up above its head
Bivalves
Molluscs of class Bivalvia
Include many species of clams, oysters, mussels, and scallops
Have a shell divided into two halves
The mantle cavity of a bivalve
Contains gills that are used for feeding as well as gas exchange
Cephalopods
Class Cephalopoda includes squids and octopuses
Carnivores with beak-like jaws surrounded by tentacles of their modified foot
Most octopuses
Creep along the sea floor in search of prey
Squids use their siphon
To fire a jet of water, which allows them to swim very quickly
One small group of shelled cephalopods
The nautiluses, survives today
Anatomy of an earthworm
Annelids are segmented worms
Annelids
Have bodies composed of a series of fused rings
The phylum Annelida is divided into three classes
Oligochaetes
Oligochaetes (class Oligochaeta)
Are named for their relatively sparse chaetae, or bristles made of chitin
Include the earthworms and a variety of aquatic species
Earthworms eat their way through the soil, extracting nutrients as the soil
moves through the alimentary canal
Which helps till the earth, making earthworms valuable to farmers
Polychaetes
Members of class Polychaeta
Possess paddlelike parapodia that function as gills and aid in locomotion
Leeches
Members of class Hirudinea
Are blood-sucking parasites, such as leeches
Nematodes are nonsegmented pseudocoelomates covered by a tough cuticle
Among the most widespread of all animals, nematodes, or roundworms
Are found in most aquatic habitats, in the soil, in moist tissues of plants,
and in the body fluids and tissues of animals
The cylindrical bodies of nematodes (phylum Nematoda)
Are covered by a tough coat called a cuticle
Some species of nematodes
Are important parasites of plants and animals
Early arthropods, such as trilobites
Showed little variation from segment to segment
: Arthropods are segmented coelomates that have an exoskeleton and jointed
appendages
Two out of every three known species of animals are arthropods
Members of the phylum Arthropoda
Are found in nearly all habitats of the biosphere
General Characteristics of Arthropods
The diversity and success of arthropods
Are largely related to their segmentation, hard exoskeleton, and jointed
appendages
As arthropods evolved
The segments fused, and the appendages became more specialized
The appendages of some living arthropods
Are modified for many different functions
The body of an arthropod
Is completely covered by the cuticle, an exoskeleton made of chitin
When an arthropod grows
It molts its exoskeleton in a process called ecdysis
Arthropods have an open circulatory system
In which fluid called hemolymph is circulated into the spaces surrounding the
tissues and organs
A variety of organs specialized for gas exchange
Have evolved in arthropods
: Arthropods are segmented coelomates that have an exoskeleton and jointed
appendages
Two out of every three known species of animals are arthropods
Members of the phylum Arthropoda
Are found in nearly all habitats of the biosphere
Molecular evidence now suggests
That living arthropods consist of four major lineages that diverged early in
the evolution of the phylum
Cheliceriforms
Cheliceriforms, subphylum Cheliceriformes
Are named for clawlike feeding appendages called chelicerae
Include spiders, ticks, mites, scorpions, and horseshoe crabs
Most of the marine cheliceriforms are extinct
But some species survive today, including the horseshoe crabs
Most modern cheliceriforms are arachnids
A group that includes spiders, scorpions, ticks, and mites
Arachnids have an abdomen and a cephalothorax
Which has six pairs of appendages, the most anterior of which are the
chelicerae
Myriapods
Subphylum Myriapoda
Includes millipedes and centipedes
Millipedes, class Diplopoda
Have a large number of legs
Each trunk segment
Has two pairs of legs
Centipedes, class Chilopoda
Are carnivores with jaw-like mandibles
Have one pair of legs per trunk segment
Insects
Subphylum Hexapoda, insects and their relatives
Are more species-rich than all other forms of life combined
Live in almost every terrestrial habitat and in fresh water
The internal anatomy of an insect
Includes several complex organ systems
Flight is obviously one key to the great success of insects
An animal that can fly
Can escape predators, find food, and disperse to new habitats much faster than
organisms that can only crawl
Many insects
Undergo metamorphosis during their development
In incomplete metamorphosis, the young, called nymphs
Resemble adults but are smaller and go through a series of molts until they
reach full size
Insects with complete metamorphosis
Have larval stages specialized for eating and growing that are known by such
names as maggot, grub, or caterpillar
The larval stage
Looks entirely different from the adult stage
Metamorphosis from the larval stage to the adult stage
Occurs during a pupal stage
Insects are classified into about 26 orders
Insects are classified into about 26 orders
Insects are classified into about 26 orders
Insects are classified into about 26 orders
The Apterygota
Protura
Collembola Springtails
Thysanura Silverfish
Diplura Two Pronged Bristle-tails
The Exopterygota
Ephemeroptera Mayflies
Odonata Dragonflies
Plecoptera Stoneflies
Grylloblatodea
Orthoptera
Phasmida Stick-Insects
Dermaptera Earwigs
Hemiptera True Bugs
Thysanoptera
The Endopterygota
Neuropter Lacewings
Coleoptera Beetles
Strepsiptera Stylops
Mecoptera Scorpionflies
Siphonaptera Fleas
Diptera True Flies
Lepidoptera Butterflies and Moths
Trichoptera Caddis Flies
Hymenoptera Ants Bees and Wasps
Crustaceans
While arachnids and insects thrive on land
Crustaceans, for the most part, have remained in marine and freshwater
environments
Crustaceans, subphylum Crustacea
Typically have biramous, branched, appendages that are extensively specialized
for feeding and locomotion
Decapods are all relatively large crustaceans
And include lobsters, crabs, crayfish, and shrimp
Planktonic crustaceans include many species of copepods
Which are among the most numerous of all animals
Barnacles are a group of mostly sessile crustaceans
Whose cuticle is hardened into a shell
Echinoderms and chordates are deuterostomes
At first glance, sea stars and other echinoderms, phylum Echinodermata
May seem to have little in common with phylum Chordata, which includes the
vertebrates
Chordates and echinoderms share characteristics of deuterostomes
Radial cleavage
Development of the coelom from the archenteron
Formation of the mouth at the end of the embryo opposite the blastopore
Echinoderms
Sea stars and most other echinoderms
Are slow-moving or sessile marine animals
A thin, bumpy or spiny skin
Covers an endoskeleton of hard calcareous plates
Unique to echinoderms is a water vascular system
A network of hydraulic canals branching into tube feet that function in
locomotion, feeding, and gas exchange
The radial anatomy of many echinoderms
Evolved secondarily from the bilateral symmetry of ancestors
Living echinoderms are divided into six classes
Sea Stars
Sea stars, class Asteroidea
Have multiple arms radiating from a central disk
The undersurfaces of the arms
Bear tube feet, each of which can act like a suction disk
Brittle Stars
Brittle stars have a distinct central disk
And long, flexible arms
Sea Urchins and Sand Dollars
Sea urchins and sand dollars have no arms
But they do have five rows of tube feet that function in movement
Sea Lilies and Feather Stars
Sea lilies
Live attached to the substrate by a stalk
Feather stars
Crawl about using their long, flexible arms
Sea Cucumbers
Sea cucumbers
Upon first inspection do not look much like other echinoderms
Lack spines, and their endoskeleton is much reduced
Sea Daisies
Sea daisies were discovered in 1986
And only two species are known
Chordates
Chordates
Phylum Chordata
Consists of two subphyla of invertebrates as well as the hagfishes and the
vertebrates
Shares many features of embryonic development with echinoderms
A summary of animal phyla
A summary of animal phyla
A summary of animal phyla
A summary of animal phyla