animals |
-multicellular -heterotrophic eukaryotes -obtain nutrients by ingestion |
ingestion |
eating food |
animals vs fungi in eating food |
-fungi absorb nutrients after digesting food outside their body -animals digest food within their body after ingesting other organisms (dead or alive ) |
animal cells |
-lack cell walls that provide strong support in bodies of plants and fungi -held together by extracellular structural proteins (abundant protein is collagen) and by unique types of intercellular junctions -almost all have muscle cells for movement and nerve cells for conducting impulses |
animal reproduction and development |
-most animals are diploid and reproduce sexually -eggs and sperm are the only haploid cells |
bastula |
– an early embryonic stage – usually a hollow ball of cells – one side of bastula folds in and cells become rearranged to form a gastrula that establishes 3 embryonic layers |
endoderm |
cell layer along the digestive tract |
ectoderm |
outer cell layer that gives rise to the outer covering of the animal |
mesoderm |
forms the muscles and most internal organs |
larva |
immature individual that looks different from the adult animal |
metamorphosis |
-major change of body form -larva goes through this and becomes an adult capable of reproducing sexually |
homeotic genes |
transformation of a zygote into an adult animal is controlled by this; the master control genes that direct animal development |
meiosis |
male and female animals make haploid gametes by meiosis; an egg and sperm fuse together making a zygote |
mitosis |
zygote divides by mitosis |
the lineage that gave rise to animals have diverged from what ancestor more than 1 billion years ago? (thought to) |
flagellated unikont |
cambrian period |
diversification appears to have been accelerated during this period (535 – 525 million years ago); many fossils found in british columbia;cambrian animals had hard body parts such as shells and spikes; scientists classified more than third of the fossils of burgess shale (sedimentary rock) to arthropods; |
what ignited the cambrian explosion? |
scientists hypothesize it happened due to increase in oxygen and increase in complex predator – prey relationship; highly probable that set of homeotic genes (genetic framework for complex bodies) was already in place; |
vertebrates |
animals with back bone; only one phylum includes this |
invertebrate |
animals without a back bone |
Animal body plans vary in: |
symmetry, presence of true tissues, number of embryonic layers, presence of a body cavity, and details of their embryonic development. |
distinctions between body plans help scientists do what? |
infer the phylogenetic relationships between animal groups |
radial symmetry |
no matter where you cut it, both halves are the same; no distinct right or left side |
bilateral symmetry |
distinct left and right sides; |
protostomes |
first opening of embryo is mouth |
deuterostomes |
second opening of embryo is mouth |
Much of the diversity in body form among the animal phyla is associated with variations in what? |
in where and when homeotic genes are expressed within developing embryos. |
body cavity (coelom) |
helps protect organs from injury |
Biologists make hypotheses about the phylogeny of animal groups using evidence from: |
body plan characteristics, the fossil record, and most recently, molecular data, chiefly DNA sequences. |
One phylogenetic tree recently revised to reflect new information distinguishes between: |
sponges ( lack true tissues) and eumetazoans (true animals); eumetazoans split into two lineages: cnidaria and and all other (cnidaria has radial symmetry and 2 layers formed in gastrulation while all the rest have bilateral symmetry with 3 layers formed- bilaterians; protostomes (ecdysozoans and lophotrochozoans) and deuterostomes (echinodermata and chordata); |
sponges |
phylum porifera; have no nerve or muscles; asymmetric; marine animals; a simple sponge resembles thick walled sac pierced with holes; waters come in through the holes to central cavity and then pours out through bigger holes; |
body of sponges |
two layers of cell; inner cell layer called choanocytes (contains flagellated cells that help to sweep water through the sponge’s body); amoebocytes produce supportive skeletal fibers (composed of flexible protein called spongin and mineralized particles called spicules); |
sponges as suspended feeders |
feed by collecting food particles suspended in water that streams through their bodies; choanocytes trap food particles in mucus on the collars and then engulf it by phagocytosis ; amoebocytes pick up food from choanocytes, digest it and pass it to other cells |
spoges movement |
cant move; are sessile; produce toxins and antibiotics to deter pathogens, parasites, and predators |
cnidarians |
radial symmetry; two tissue layers; have outer epidermis and an inner cell layer that lines the digestive cavity; carnivores (use their tentacles to eat small animals and protists); named after their stinging cells (cnidocytes) used to kill animals and in defense; |
cindarians exhibit two kinds of body forms: |
polyp (hydras, sea anemones- cylindrical body with tentacles extending from one end) and medusa (jellyfish); some cnidarians pass from one body form to another (polyp -> medusae) while others only stay at one form |
polyps vs medusa |
polyps are stationary but medusae move freely; polyp mouth is upward, medusae mouth is downwards |
gastrovascular cavity in cnidarians |
cnidarians mouth leads to this; which functions in digestion, in circulation, and as a hydrostatic skeleton; one opening |
flatworms |
phylum platyhelminthes; belong to lophotrochozoan lineage of bilaterians; bilateral symmetry and three tissue layers; lack body cavity; live in marine, freshwater and damp terrestrial habitats; have gastrovascular cavity that distributes food throughout the animal; one opening |
three major group of flatworms |
free living flatworms, flukes, tapeworms |
free living flatworms |
planarians; eyes and other sense organs contact the environment first; feeds through a mouth that is at the tip of muscular tube; live on the undersurface of rocks in freshwater ponds and streams; have heads with light-sensitive eyecups, flaps to detect chemicals, dense clusters of nerve cells that form a simple brain and a pair of nerve cords that run the length of the body, and a branched gastrovascular cavity with a single opening. |
flukes |
live as parasites in other animals; nearly made up of reproductive organs; suckers that attach to their hosts; |
tapeworms |
parasitic group of flatworms; inhabit the digestive tract of vertebrates; long ribbon like body with repeated units; absorb nutrients across their body surface and have no digestive tract; have units at the posterior end that are full of ripe eggs that pass out of the host’s body through feces |
nematodes |
roundworms; phylum nematoda; bilateral symmetry with 3 tissue layers; in contrast with flatworms, roundworms have fluid filled body cavity (that functions to distribute nutrients) and a digestive tract with two openings; important decomposers in soil and on the bottom of lake and oceans |
nematodes body |
are cylindrical with a blunt head and tapered tail; several layers of touch non living material called a cuticle covers the body and prevents it from drying out; cuticle also protects them from the host’s digestive system; |
nemotodes digestion |
have a complete digestive tract, extending as a tube from mouth to anus; food travels from one way through the system and is processed as it moves along; advantage is that different part of the tract can be specialized in different functions; |
molluscs |
phylum mollusca; soft bodied animals protected by hard shell; ex: snails, slugs, oysters, clams, squids; have separate sexes with reproductive organs situated in visceral mass; members of lophotrochozoan lineage; have a body cavity and complex organs and organ system; they have open circulatory system (pumps blood and distributes nutrients and oxygen throughout the body); 3 diverse types: gastropods, cephalopods; bivalvia |
3 main body parts of molluscs |
muscular foot (functions in locomotion); visceral mass (contains most of the internal organs) and mantle (a fold of tissue that drapes over the visceral mass and secretes a shell) – mantle extends beyond the visceral mass producing a water filled chamber called mantle cavity (houses the gills) |
radula |
many molluscs have this; this is used to scrape up food |
gastropod |
"Stomach foot"; snails and slugs; found in fresh water, salt water and terrestrial environments; only molluscs that live on land; protected by single spiraled shell in which the animal can retreat when threatened; |
bivalvia |
clams, oysters, mussels and scallops; shells divided into two halves that are joined together; suspended feeders; mantle cavity contains gills that are used for feeding and gas exchange; sedentary (living in sand or mud); |
cephalopods |
"head foot"; predators; octopus, squid; use beak like jaws and a radula to crush their prey apart; have large brains and sophisticated sense organs; |
annelids |
phylum annelida; segmened body; lophotrochozoans lineage; segmentation played a key role in the evolution of many complex animals; segments = great flexibility and mobility; found in damp soil, in sea and in most freshwater; three main groups: earthworms, leeches, polychaetes |
earthworms |
many intern body structures are repeated with segments; nervous system includes a simple brain and ventral nerve cord; digestive tract not segmented; closed circulatory system; hermaphrodites- contain both male and female reproductive structures; ingest soil and extract nutrients, aerating soil and improving its texture. |
polychaetes |
"many hair"; marine; sandworms; have stiff bristles on appendages that helps the worm wriggle around;search for prey on the seafloor or live in tubes and filter food particles. |
leeches |
free living carnivores that eat snails and insects; sting contains anesthetic and anticoagulant (can dissolve blood clots); |
closed circulatory system |
blood remains enclosed in vessels as it distributes nutrients and oxygen throughout the body |
open circulatory system |
blood is pumped through vessels that open into body cavities where organs are bathed in blood |
athropods |
crayfish, lobsters, crabs, spiders, insects, ticks; diversity and success related to their segmentation, hard skeleton, and jointed appendages; ecdysozoan lineage; body and appendage covered with exoskeleton (an external skeleton that protects the animal); cuticle hardened by layers of protein and chitin; arthropod must shed its old exoskeleton to grow; this process called molting, or ecdysis; open circulatory system; four major lineages: insects, chelicerates, crustaceans, millipedes and centipedes |
athropod appendage |
adapted for sensory reception, defense, feeding, walking and swimming |
chelicerates |
horseshoe crab; scorpions, spiders, ticks and mites collectively called arachnids; most arachnids live on land. |
millipedes and centipedes |
millipedes have two pairs of short legs per body segment, eat decaying plant matter; centipede have single pair of legs per segment, carnivore- eat flies, cockroaches |
crustaceans |
lobster, crayfish, crab, shrimp; |
list characteristics arthropods have in common. |
hard skeleton; specialized joint appendages; segmentation |
insects |
make up nearly 75% of all animal species; can fly, waterproof coating on cuticle and have complex life cycle; 3 pair of legs; |
insect life cycle |
metamorphosis; more than 80% of insects goes though complete metamorphosis; the larval stage is specialized for eating and growing; the insect then emerges as an adult to reproduce; |
insects modular body plan |
each embryonic segment is a separate building block that develops independently of the other segments; a mutation that changes homeotic gene expression can change the structure of one segment without affecting other segments |
The extraordinary success of insects is due to: |
body segmentation, an exoskeleton, jointed appendages, flight, a waterproof cuticle, and a complex life cycle with short generations and large numbers of offspring. |
complete metamorphosis |
free-living larva transforms from a pupa into an adult. |
incomplete metamorphosis |
transition from larva to adult is achieved through multiple molts, but without forming a pupa. |
echinoderms |
sea stars, sand dollars, sea urchins; slow moving or sessile marine animals; most are radially symmetric as adults; water vascular system (a network of water filled canals that branch into tube feet); tube feet functions in locomotion, feeding, and gas exchange; capable of regeneration; have endoskeleton of hard calcium-containing plates under a thin skin; |
the arthropod body plan is a key factor in evolutionary success; how did this happen? |
there were two hypothesis; |
first hypothesis of why the arthropod body plan is successful |
increase in the number of homeotic genes led to the diversity of segment and appendage types in arthropods (proved false because velvet worms had same set of arthropod homeotic genes – conclusion: body segments did not arise from new homeotic genes ) |
second hypothesis of why the arthropod body plan is successful |
changes in the regulation of homeotic gene expression (when and where the genes are transcribed and translated into proteins) led to the diversity of segment and appendage types in arthropods; Such changes in developmental genes are known to result in significant morphological changes; proven true |
chordates features that they share with invertebrate ancestors |
1) dorsal, hollow nerve cord 2) notochord (a flexible supportive rod located between the digestive tract and the nerve cord); 3) pharyngeal slits located in the pharynx; 4) a muscular post anal tail; tunicate and lancelet = invertebrate chordates; although not unique, body segmentation is a characteristic of chordata; |
tunicate |
adult tunicate has no trace of a notochord, nerve cord, or tail; stationary and attached; tunicate larva has all four distinctive chordates features; suspension feeders; molecular evidence suggests that these are the closest living non vertebrate relatives of vertebrates |
lancelets |
suspension feeders; exhibit the four distinctive chordate features; represent earliest branch of chordate lineage; |
Invertebrates do what for humans |
play critical roles in natural ecosystems and; provide valuable services to humans; Reef-building corals create enormous structures that provide support and shelter for hundreds of other species; Reef-dwelling cone snails produce a powerful painkiller in their venom; Freshwater mussels filter and improve water quality in natural ecosystems and reduce the cost of water treatment for human uses. |
A researcher discovers a mysterious unknown multicellular eukaryotic organism. She would be confident that it is an animal if she observed that it __________. |
A Muscles and nerves are typical of many animals but are not found in any other multicellular eukaryotes. Their presence would strongly indicate that the mystery organism is an animal. |
Suppose you could travel back to the Cambrian period in a time machine and carry a full laboratory along with you. To better understand the Cambrian explosion, you might want to _____. |
D |
All animals can probably trace their lineage to a common ancestor that lived in the __________. |
B |
Most animals are _____. |
B |
A researcher finds an animal from a previously unrecognized group. Shee dissects it and finds that it clearly has a true coelom. What additional properties could she check next to further categorize this animal? |
A |
The presence of a coelom or other form of body cavity is advantageous because it _____. |
D A body cavity enables the internal organs to grow and move independently of the outer body wall while being protected from injury. |
Our most current understanding of animal phylogeny is based on __________. |
A |
A spectacular marine animal has a network of glassy spicules that forms a cagelike structure. This animal does not have true tissues. It is a suspension feeder. What cells or structures does this cage-building animal use to get nutrients from its feeding cells to other parts of its body? |
B |
Among animals, sponges are unique in that they _____. |
B |
A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A professor thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus? |
A Fungal cells have cell walls, and animal cells do not. |
Animals of one common phylum are NOT bilaterians but are eumetazoans. What phylum is it? |
D |
If an organism is a protostome, what else can you conclude about its body plan? |
A |
Which lists the three tissue layers in a typical animal in the correct order, starting from inside the digestive tract? |
C |
Zoologists place chordates and echinoderms on one major branch of the animal phylogenetic tree, and molluscs, annelids, arthropods, and many other phyla on other major branches. Which of the following is a basis for this separation? |
B |
Which combination of features would occur in a typical animal? |
C |
The phrase "Cambrian explosion" refers to _____. |
C |
Which of the following is associated with bilateral symmetry? |
B |
Sponges typically feed by _____. |
D |
Which of the following is radially symmetrical? |
A |
An animal is called a protostome or a deuterostome based on _____. |
C |
The presence of a coelom or other form of body cavity is advantageous because it _____. |
C |
The difference between pseudocoelomates and animals with a true coelom is that pseudocoelomates _____ whereas coelomates _____. |
C |
The body cavity of a soft-bodied animal typically functions as a _____. |
B |
The animal phylum most like the protists that gave rise to the animals is _____. |
B |
Animals of one common phylum are NOT bilaterians but ARE eumetazoans. What phylum is it? |
C |
Digestion in sponges takes place in the _____. |
C |
Jellies (also incorrectly called "jellyfish") and coral animals both _____. |
C |
Cnidaria have both _____. |
A |
How do coral animals obtain their food? |
A |
How do cnidarians differ from the other common animal phyla profiled in this chapter? |
B |
You are given an unknown animal to study in the laboratory. It is long and ribbonlike and appears to be segmented. You find it has three tissue layers, it does not have a digestive tract, and it has male and female reproductive structures in the same individual. This animal probably is a(n) _____. |
C |
Biology deals with many kinds of worms. Which choice includes three different phyla of "worms"? |
Platyhelminthes, Annelida, Nematoda |
Which option correctly describes a nematode? |
C |
An active marine predator is found possessing these characteristics: a series of tentacles (modified from the foot), a highly developed nervous system, and elaborate image-forming eyes. This organism is most likely a(n) _____. |
C |
You go to the supermarket and ask a clerk where you can find the gastropods. He takes you to the "weird food" section and points out a container of _____. |
A |
Choose the option that correctly matches each mollusc class to its typical lifestyle. |
D |
Consider the following list of animals: giant squid, earthworm, fish, snail, tapeworm, coral, and sea star. The two that belong to the same phylum are the _____, and their phylum is _____. |
B |
Leeches are members of the phylum _____. |
B |
Earthworms are most closely related to _____. |
A |
While dissecting an earthworm, you notice a closed tube that sits atop the digestive tract. Within each segment, this dorsal tube has a pair of branches that extend to connect with a similar ventral tube. What are you looking at? |
A |
The arthropods superficially resemble earthworms in that both groups have _____, yet the two are distinctly different because arthropods, but not earthworms, _____. |
D |
The phylum _____ includes the largest number of species of all animal phyla. |
A |
In arthropods, molting is necessary because _____. |
D |
Which of the following animals is most closely related to spiders? |
C |
The majority of animal species are _____. |
C |
Complete metamorphosis _____. |
B |
A sea star and a sea jelly belong to the phyla _____ and _____, respectively. |
D |
The water vascular system of a sea star functions in _____. |
D |
Which correctly describes Echinodermata? |
B |
Sea stars and sea urchins are members of the phylum _____. |
B |
An animal has segments, bilateral symmetry, pharyngeal gill slits, a post-anal tail, and deuterostomic development. It must be a member of the phylum _____. |
A |
A _____ is a chordate but not a vertebrate. |
D |
Which chordate is a stationary, globular suspension feeder as an adult? |
D |
Chordates are deuterostomes, and their closest relatives among the common phyla we have reviewed are _____. |
B |
The two major groups of protostomes in the "new" phylogeny of animals are _____. |
A |
Which of the following is thought to be most closely related to humans? |
C |
Which of the following most clearly demonstrates the evolutionary relationship between nematodes and arthropods? |
B |
Which field of research investigates how developmental patterns evolve and give rise to new features in animals? |
C |
You are a researcher studying development in the chicken and identify a previously unknown gene that is expressed in the early embryonic cells that eventually differentiate to become liver cells. The gene plays a role in directing the development of this organ. Where else might you expect to find very similar homologous genes expressed? |
D |
Which phyla both possess a gastrovascular cavity that has only one opening? |
C |
In the ocean, you find an organism with a hard exoskeleton and jointed legs. It is _____. |
D |
Which feature of insects has promoted their diversification and evolutionary success? |
D |
Which characteristic is unique to Chordata (it is a diagnostic feature) and is evident at some stage of the life cycle in all chordates? |
B |
Compared to fruit flies, humans have _____. |
A |
Fascioloides magna is an animal that lives in the livers of deer in the southeastern United States. It has a bilaterally symmetrical, flattened leaf-like body with a digestive tract with a single opening. It also lives in a snail for part of its life cycle. This animal is most likely a _____. |
fluke |
A group of parasites called myxozoans have traditionally been considered simple multicellular protists. However, because these organisms possess stinging cells, some scientists consider them to be animals in the phylum that is named for such cells, the _____. |
cnidarians |
Dracunculus medinensis is a parasite that can grow to be one meter long, and which humans can acquire through contaminated drinking water. Which of the following traits would allow you to place this animal unambiguously in either the Platyhelminthes or Nematoda phyla? |
pseudocoelom |
Schistosomiasis is a debilitating disease that affects some 200 million people. It is caused by a parasitic flatworm that is transmitted to humans through contact with an air-breathing mollusc. The parasite and mollusc, respectively, are _____. |
flukes and snails |
A medicinal annelid applied to drain blood from a patient. leeches, a type of annelid |
leeches, a type of annelid |
At the Sand Bar restaurant, customers can nibble on snails (_____) with garlic butter and oysters on the half shell (_____) during their "happy hour." The happy patrons will be enjoying what types of molluscs? |
gastropods … bivalves |
What is the difference between complete and incomplete metamorphosis? |
Insects that undergo incomplete metamorphosis do not form pupae. |
When comparing gene content and gene expression of homeotic genes in arthropods versus velvet worms, scientists discovered __________. |
arthropods and velvet worms have the same set of genes, but these are expressed at different body locations in each group of animals |
Sea daisies are tiny marine animals found in deep water. These animals have a water vascular system, overlapping skeletal plates, and calcareous spines. Which of the features below would you expect them to also possess in the adult stage? |
deuterostome development |
Pikaia gracilens is an extinct invertebrate animal described from the wonderful pre-Cambrian soft-bodied fossils of the Burgess Shale in British Columbia. Examinations by paleontologists have revealed that organisms belonging to this species had a prominent notochord and segmental muscles. From this information, you could conclude that it is closely related to __________. |
lancelets |
Cephalaspids are an extinct group of vertebrates that possessed paired fins but no jaws. This group could be considered to be relatively advanced __________ that are ancestral to __________. |
lampreys; sharks and rays |
biology chapter 18
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