bio 2 exam 4 & 5

1. Describe the species and morphological diversity within Kingdom Animalia.

• 8.7m extant spp (60,000 vertebrates)

• animals have common ancestor with fungi 460MYA

• diverse in form and habitat

3. Summarize the general features of animals and determine whether that feature is
common to all animals or found in only a subset of animals.

all

• heterotrophic

• multicellular

• no cell walls

• complex embyonic development

most (sponges are the exception)

• complex tissues

• complex movement

4. Define tissues, explain their benefits, and describe their role in complex
movement, comparing animal movement to single-celled organisms.

tissues- groups of cells with a particular morphology and function

• allows for specialization

• tissues differentiate throughout embryonic development

• zygote is totipotent= can differentiate into any type of cell/ tissue

• only animals have nerve and muscle tissue for complex movement, allows for flexibility in their lifetime

5. Summarize animal development from zygote to gastrula and compare protostome
and deuterostome development (blastopore, cleavage, determinant/
indeterminant development)

cleavage: early mitotic division of the zygote, patterns differ based on animal group

spiral cleavage: protostomes, turns

radial cleavage: deuterostomes, right on top of 1st layer

determinant: type of tissue is determined early in development, protostomes

indeterminant: first few cell divisions stay totipotent, deuterostomes

protostomes: blastopore becomes mouth

deuterostomes: blastopore becomes anus

6. Identify the three germ layers, their distribution among animals, and their
developmental fate.

1. ectoderm: outer covering, nervous system

2. mesoderm: skeletal and muscular system

3. endoderm: digestive system

all 3 = triploblastic

endo and ecto = diploblastic

7. Define and describe body cavities, comparing acoelomates, pseudocoelomates,
and coelomates in form and function.

• acoelomates= no cavity (flatworm)

• pseudocoelomates= “false cavity” develops between meso and endo (roundworm)

• coelomates= cavity entirely in meso (annelid)

- isolated cavity inside body

- allowed for evolution of complex and more efficient organ systems

- shared resources, allows for freedom of movement and interaction between organs

8. Describe patterns of symmetry and their evolutionary significance, including links
to cephalization and segmentation.

radial: any line passing through central axis divides the animal into mirror halves

bilateral: the body has right and left halves that are mirror images divided by sagittal plane

9. Use ontogeny terms to describe animal structures.

• anterior: head

• posterior: butt

• dorsal: top

• ventral: bottom

• proximal: shoulder, towards head

• distal: towards fingers, away from head

• medial: middle

• lateral: sides

• oral: top

• aboral: bottom

11. Describe the species diversity, typical habitat and defining characteristics of
phylum porifera

• produces chemicals to deter others from overgrowing or predators, these may be useful pharmaceuticals

• 26,000 spp

• motile planktonic larvae

• mostly marine (150 freshwater)

• occur at all depths (abundant in the deep sea)

• no tissues, symmetry, or movement

12. Summarize the body layers and cell types observed in phylum porifera, including
the role different sponge cell types play in feeding, defense, and reproduction.

• mesohyl: middle layer of sponge

  • primarily made of collagen, protein rich matrix

  • filled with totipotent amoebocytes

  • some sponges produce tough spongin fibers, and spicules (needles of calcium carbonate or silica)

• epithelial: protective layer, specialized cells surrounding ostia contract to close the pores

• choanocytes: (collar cells) inner layer responsible for feeding and water circulation

  • resemble protists with one flagella

  • flagella create water currents for feeding, oxygen and capturing food via engulfing

specifics of the water flow and pore system in sponges

• ostia: openings for water entering

• porocytes: cells controlling ostia opening/closing

• osculum: large exit for filtered water

specifics of defense system in sponges

• sclerocytes/spongocytes: secrete spicules for structure and defense

• myocytes: conduct signals for contraction

13. Compare and contrast asexual and sexual reproduction in phylum porifera.

• asexual: fragmentation

• sexual:

  • some choanocytes transform into sperm, which are released into the water

  • in sperm are pulled into the ostia of another sponge of the same spp, they will be carried to the egg in the mesohyl

  • motile (ciliated) larvae develops and undergoes a short planktonic (drifting) stage

  • larvae settles on suitable substrate and becomes an adult

16. Describe the species diversity, typical habitat and defining characteristics of
phylum cnidaria.

• 10,000spp, mostly marine, radial symmetry

• have tissues, no organs, are diploblastic

• carnivorous, nematocysts, hydrostatic skeleton

• digestion in gastrovascular cavity

• 2 body plans: polyp and medusa (this makes them dimorphic)

• “nerve net”

17. Describe the cnidarian nervous system

• cnidarians have nerves, but those cells are not connected to a brain or ganglion

• nerve cells distributed throughout the body in an interconnected nerve net

• allows for sophisticated nervous system activity, including touch, gravity, and light receptors (including image forming eyes)

18. List the two basic body plans observed in phylum cnidaria

polyp:

• cylindrical (bilateral symmetry)

• sedentary= attached to substrate

• mouth surrounded by tentacles at one end (opposite of the attachment)

• ex. anemone

medusa:

• umbrella shaped (radial symmetry)

• free living

• mouth surrounded by tentacles at one side

• ex. jellyfish

19. Summarize cnidarian body layers and describe how the cnidarian body layers are
arranged in relation to the mesoglea and gastrovascular cavity

• single opening (mouth) leading to a gastrovascular cavity

  • feeding, gas exchange, gamete formation

• 2 body layers

  • epidermis= contacts outside environment

  • gastrodermis= lines gastrovascular cavity

• mesoglea: jelly-like layer between 2 body layers

20. Define and describe the form and function of the cnidarian hydrostatic skeleton

• the gastrovascular cavity of cnidarians acts as a hydrostatic skeleton

  • rigid structure against which muscles can operate

  • gives animal shape

• to work, a fluid filled cavity must close tightly so fluid is under pressure, cnidarians must hold this mouth closed to use the hydrostatic skeleton

21. List the specialized cells/structures involved in cnidarian feeding and defense

• use extracellular digestion inside their gastrovascular cavity, allows for consumption of large prey

• they contain specialized cells called cnidocytes “stinging cells” containing organelles called nematocysts “stingers” used to capture prey stinging capsules secreted within the nematocysts (thousands per tentacle and can only be used once)

• capsule springs open and emits tubule (can be barbed and or venomous)

23. Describe cnidarian reproduction

sexual:

• spawning: release sperm and eggs into water column

• driven by environmental cues “mass spawning events”

• fertilized egg=zygote, forms planula larva that has cilia, moves to suitable substrate to grow into a polyp

polyps produce asexually:

• via budding

• however, transverse fission is an option, to form ephyra, this is a sexual form that results in medusa

26. Describe the overall species diversity, typical habitat, and defining features of four
scyphozoans, cubozoans, hydrozoans and anthozoans

scyphozoa:

• jellyfish

• 350spp

• marine

• medusa

• polyp smaller or lacking

• moves by pulsating contraction of the bell

cubozoa:

• box jellies

• 90spp

• marine

• medusa

• polyp smaller or lacking

• image forming eyes

hydrozoa:

• 6000spp

• marine and freshwater

• almost all have both polyp and medusa

• only class with freshwater spp (hydra)

anthozoa:

• coral and anemones

• 6200spp

• marine

• polyps

• compartmentalized gastrovascular cavity

27. Describe how coral reefs form and summarize their economic and environmental
importance including the process of coral reef beaching and the impact coral reef
bleaching has on the environment

• most anthozoans are hard corals

• polyps secrete exoskeleton of calcium carbonate

• as colony grows, dead skeleton accumulates below, forming reefs

• typically form in shallow, nutrient poor environments, supported by photosynthetic symbionts

• very diverse

  • home to 25% of all known marine spp

  • house young fish

  • protect coasts

• bleaching:

  • increasing water temp. due to climate change causes symbiosis to break down

  • causes the skeleton to become visible

28. Describe the defining features of protostomes and list their two major clades.

spiralia and ecdysozoa

• ” first mouth”

• zygote blastula gastrula

• blastopore develops into the mouth

• ex. worms, mollusks, arthropods

29. Describe the defining features of the spiralia and list their two major clades

platyzoa:

• “flat animals”

• no circulatory

• no respiratory

• complex reproductive

• ex. dug

lophotrochozoa:

• many have a free living trochophore larvae

• many have a locophore= feeding structure compromised of tentacles around a mouth used in filter feeding

30. Describe the defining features of the ecdysozoa.

• animals that molt (ecdysis)

• molt due to their exoskeletons

31. Describe the defining features, species diversity and typical habitat of
platyhelminths

• 55,000spp

• free living:

  • marine

  • freshwater

  • terrestrial

  • parasitic

• ciliated

• softbodied

• dorsoventrally flattened

• bilateral symmetry

• complex repro and life cycle

• triploblastic

• acoelomates

• incomplete digestive system

32. Identity which group of protostomes Platyhelminthes belong to and the
evolutionary relationship between Platyhelminthes and other organisms covered
in this course.

protostomes - sprialia - platyzoa - platyhelminthes

33. Describe how and where food intake digestion occurs in Platyhelminthes.

• single opening (mouth) to digestive cavity

• mouth located midbody, on ventral side, on pharynx

• ingests food through mouth, which travels down the pharynx where muscle contraction breaks it down

• digestion occurs in the gut: most digestion occurs extracellularly, cells lining the gut wall take in some food by phagocytosis to complete digestion

• branches of the gut extend throughout the body to

  • increase surface area

  • aid in the transport of molecules around the body

34. Describe the form and function of the typical Platyhelminthes nervous system

• composed of an anterior cerebral ganglion and nerve cords (transvers and longitudinal) that run down the body

• ganglion: a collection of nerve bodies found in the peripheral nervous system

35. Summarize reproduction in Platyhelminthes including the names and locations of
the structures involved in Platyhelminthes reproduction

• most are hermaphroditic

• fertilization is internal (requires 2 individuals)

  • each deposits sperm into the copulatory sac of the other and sperm travels to reach egg through specialized ducts

• fertilized eggs are laid in a cocoon

• eggs hatch into either a mini adult (freshwater) or a larvae (marine)

36. List the two major groups of flatworms.

free living:

• turbellaria

• ex. dug

parasitic:

• subphyla neodermata “new skin”

• nerodermis (also called tegument)

  • trematoda: flukes

  • cestoda: tapeworms

• evidence suggests parasitism has evolved only once in plathelminthes from a free living ancestor

37. Describe the defining characteristics, species diversity, typical habitat and life
cycle of flukes.

• 10,000spp

• parasites

• attach to the host with suckers or hooks

• feeds on host through mouth

• life cycle typically involves more than one host

  • transfer is risky

38. Describe the defining characteristics, species diversity, typical habitat and life
cycle of tapeworms

• 5,000spp

• intestinal parasites

• attach to wall of hosts intestine

• no digestive cavity

• absorb food through body wall

39. Describe the form and function of proglottids

• scolex: attachment structure

  • not a head, no mouth or concentration of nervous tissue

• neck

• proglottids: series of repetitive sections

  • every unit is hermaphroditic

  • formed continuously at a growth zone at the base zone of the neck

  • mature proglottids are pushed posteriorly

  • terminal proglottids fills with embryos, breaks off, and is carries out in animal feces

  • offspring attack to the environment and get picked up by another animal

what do the ostia and osculum do in sponges?

In sponges, ostia are multiple pores on the body wall that allow water to enter the spongocoel. Osculum is a large common opening that expels water from the spongocoel

function of choanocytes in sponges?

choanocytes (collar cells), which are flagellated cells, aid the movement of water through the sponge, thereby helping the sponge to trap and ingest food particles

function of amoebocytes in sponges?

Amoebocytes have a variety of functions:

• delivering nutrients from choanocytes to other cells within the sponge

• giving rise to eggs for sexual reproduction

• delivering phagocytized sperm from choanocytes to eggs

what is a bipartite life cycle? and what are the stages of it in anemones?

means that different life stages live in different areas, the larvae is benthic, the ephyra is pelagic

what is the function of the acontia and pedal disk in anemones?

• Acontia are unique defense tissue in acontiarian sea anemones. They protrude through the body wall upon attack by predators or artificial stimulation.

• Pedal disk is used for attachment to the substratum. It is part of the anemone's body plan and plays a role in adhesion

what is a polymorphic life cycle?

it means an organism goes through different forms throughout their life cycle, ex. polyp to medusa

which group within kingdom Protista probably gave rise to sponges? on what evidence do you base your answer?

The group within kingdom Protista that probably gave rise to sponges is choanoflagellates. Evidence for this includes the presence of choanocytes in both choanoflagellates and sponges

why are spicules used as a primary characteristic to classify sponges?

Spicules have been used to delimit species because they vary in their composition, size and morphology, and branching patterns.

sponges and cnidarians have no lungs or gills. How do they exchange gases within the environment? Are humans better off having lungs? how so?

• Gas exchange in sponges and cnidarians occurs via simple diffusion between the water and the cells bathed in it. This process works well for small organisms in which the diffusion distance is relatively short.

• In humans, the diffusion distance is much greater. As such, a more complex system of gas exchange has evolved over time.

why are sponges considered to be an evolutionary dead end?

because no clear descendants from sponges exist as determined by fossil record

explain how cnidocytes with their nematocysts function in food capture and defense.

Nematocysts are released by cnidocytes. These thread-like harpoons impale their prey and inject a toxin that immobilizes them.

discuss how polymorphism in the cnidarians might have influenced adaptive radiation of the group.

• polymorphism in cnidarians resulted in the formation of different life forms that have different functions.

• The production of different life forms may have influenced adaptive radiation, allowing these forms to adapt to different environments over time.

how does digestion in cnidarians differ from digestion in sponges?

• Sponges rely on intracellular digestive processes because they have no true digestive systems.

• Cnidarians rely on both extracellular and intracellular digestion

Flatworms are the first organisms we have discussed with an anterior-posterior orientation. How does this affect their movement compared to more primitive organisms?

The orientation of light-sensitive eyespots and development of a more centralized nervous system results in a more coordinated response to stimuli and directional movement.

what are the disadvantages of a flatworms digestive system having only one opening?

The primary disadvantage of possessing a single opening associated with the digestive system is that the rate food intake is limited because undigested wastes are egested through the same opening. In addition, this more primitive digestive system typically consists of a gastrovascular cavity void of specialized compartments having distinct and different functions.

the complete digestive tract of mollusks and other phyla allows functional specialization. what specializations are common in the digestive tract of higher organisms such as humans?

The digestive tract of "higher organisms" vary but typically consists of 1.) esophagus (movement of food particles), 2.) a stomach (maceration, digestion, and movement of food particles), 3) a small intestine (digestion and absorption of nutrients, and movement of waste), and large intestine/cecum (water absorption and waste storage and removal).

what is the advantage of radial symmetry for sessile animals such as hydra and bilateral symmetry for mobile animals such as planaria? what major evolutionary trends accompany bilateral symmetry?

Radial body symmetry is often associated with sessile or planktonic organisms ( i.e. relatively immoblie), thus this type of body plan and structures allows these organisms to detect prey and danger and procure food from alomst any direction. Organism with bilateral symmetry often possess greater specialization associated with movement associated with cephalization.

mollusks exhibit a variety of feeding methods. list at least four and discuss adaptations and examples for each type.

Predators such as cephalopods have tentacles and discs to capture prey and "beak" to tear flesh.
Scrapersuch as gastropods have a radula.
Herbivores graze on algae or macrophytes.
Filter feeders such as oysters have cilia that can capture food particles and route them to the mouth.

a small shell is quite different from the familiar bony section of a mammal. in what ways does a shell function as a skeleton?

Structure for attachment of muscle.
Protection from predators/ environment.
Mineral reserve and growth.
Contains other body systems.

some land snails have formed a lunglike structure from a major layer of tissue. what is that layer?

mantle

cephalopods are considered by many to be the most distinctive class of mollusks. what makes them seem almost out of place?

Highly developed nervous system, problem solving and learning ability. More complex than other mollusks. They have eyes much like ours.

Describe the defining features of the lophotrochozoa

• Many have a free-living trochophore larvae

• Many have a lophophore (feeding structure
  comprised of tentacles around a mouth used in
  filter feeding)

• THEY WILL HAVE ONE OR THE OTHER, EX. ANNELIDS AND MOLLUSKS BOTH HAVE TROCHOPHORE LARVAE

List the two phyla of lophotrochaozoa addressed in this course

Annelida and Mollusca

Describe the diversity of species, habitat and characteristics of phylum Mollusca

• Over 150,000 species (2nd biggest to
  Arthropods)

• Morphologically diverse
  • Microscopic to giant (giant squid)
  • Marine (most), freshwater, terrestrial

• • Have tissues and organs
  • Bilaterally symmetrical
  • Triploblastic
  • Coelomates
  • Complete digestive system
  • Often shelled

• culturally, economically, and environmentally important

List and describe 3 major internal morphological features of mollusks

Reduced Coelom
• Mollusks have a true coelom, but it is highly reduced — only small fluid-filled spaces around organs like the heart and gonads.
• In other invertebrates (like annelids), the coelom acts as a hydrostatic skeleton.
• In mollusks, the shell provides structural support, replacing this function.
Visceral Mass
• Central area that holds most of the internal organs
Mantle
• A sheet of epidermal tissue covering the dorsal side of the body.
• Functions:
• Secretes calcium carbonate to form the shell
• Surrounds mantle cavity, which is used for respiration, excretion, and reproduction
Mantle Cavity & Ctenidia (gills)
• Ctenidia are gill-like, ciliated structures that:
• Project into the mantle cavity
• Move water over blood-rich filaments for gas exchange
• Help filter food in some mollusks

List and describe the structure and function of the 3 major external morphological features of mollusks

Shell
• Calcium carbonate
• Secreted by the mantle
• Protection from predators and the environment
• Reduced and internalized shells have evolved repeatedly
• slugs, squid, octopus, cuttlefish
Foot
• Muscular structure used for locomotion, food capture, digging, etc.
• Snails/slugs – movement, secrets mucus
• Bivalves – digging
• Cephalopods – food dividend into tentacles/arms
Radula
• Rasping, tongue-like structure used for feeding.
• Contains 100s of teeth arranged in rows.
• Only completely absent in bivalves

Describe the general steps in mollusk reproduction

• Most have separate sexes and
reproduce by external fertilization (dioecious)
• Spiral cleavage
• Embryo develops into free-swimming
trochophore larvae.
• Swims by cilia around center of body
• Marine gastropods and bivalves then
develop into second free-swimming
stage called veliger (has foot, shell
and mantle).

List the three major classes of mollusks, including their species diversity, habitat and characteristics (gastropoda Bivalvia, cephalopoda)

Class Gastropoda
• ~60,000 species
• Marine (most), freshwater, terrestrial
• Mantle cavity modified to lung in terrestrial species
• Undergo torsion during development

Class Bivalvia
• ~10,000 species
• Marine (most), freshwater (~500 species)
• Two shells with dorsal hinge
• Ligament along hinge keeps it open
• Adductor muscles link shells internally and
contract to close shell
• No radula
• No head
• Filter feeders with siphons
• Water enters mantle cavity through inhalant
siphon and exits through separate exhalant
siphon

Class Cephalopoda
• ~700 species
• Marine
• Only mollusk with a closed circulatory system
• Foot evolved into arms
• Predators (beak-like jaw & radula)
• Largest invertebrate brain
• Vertebrate-like eyes (evolved independently)
• Most lack external shell

Describe torsion in gastropods

Undergo torsion during development
• Twisting of body so that mantle cavity and anus are moved
toward the head
• Not coiling
• Not bilaterally symmetrical

Describe the structure and function of chromatophores

• Match environmental background
• Communicate with one another
• Chromatophores – elastic, pigment-containing epithelial
cells
• Attached to radial muscles that alter the cells to reveal the
pigment

Describe the species diversity, habitat and characteristics of phylum annelida

• Diversity:
• ~9,000 species
• Habitat:
• Marine, freshwater, terrestrial
• Characteristics:
• Have tissues and organs
• Bilaterally symmetrical
• Triploblastic
• Coelomates
• Complete digestive system
• Segmented
• Well developed cerebral ganglion
and sensory organs are localized
to the anterior end

Describe the structure and function of annelid segmentation, what structures are found in each annelid segment, and how segmentation
influences movement

• During development the head and tail form first,
followed by the segments in between.
• Each segment is divided by a septa
• Each segment contains
• Excretory organs
• Ganglia
• Locomotor structures
• Reproductive structures
• Some communication across segments
(example: closed circulatory system)
• Move by constricting segments
• Coelomic fluid creates hydrostatic skeleton that
makes segment rigid. Muscles move to shorten and
elongate segments around that hydrostatic
structure.

List the two classes of annelids discussed in this course

polychaeta and clitellata

Describe the species diversity, habitat and characteristics of class polychaeta. Clitellate, oligochaete, and hirudinea

Class Polychaeta
• ~8,000 species
• Marine
• Segments have parapodia which bear
chaetae.
• Swimming, borrowing, crawling
• Gas exchange – like gills (increase surface
area of body)
• Filter feeders – feathery tentacles that
sweep water to collect food
• Predators - can incorporate metals into
jaws to harden

Class Clitellata
• Modern classification of
earthworms and
leeches based on their
shared clitellum.
• Raised band that
contains reproductive
structures.

Earthworms (subclass oligochaete)
• ~7,000 species
• Terrestrial
• 100-175 segments
• Clitellum
• No parapodia
• Has a few small chaetae that project directly from
the body wall
• Hermaphroditic
• Exchange sperm at the clitellum
• Clitellum forms cocoon that the worm passes through
• Eggs are incorporated as cocoon passes over female
reproductive structures
• Cocoon passes over entire worm, seals, and is left
behind.
• Environmentally important for aerating and
loosening soil

Leeches (subclass Hirudinea)
• 680 species
• Most 2-6cm – some 30cm!
• Freshwater (most), marine
• Dorsoventrally flattened
• Hermaphroditic
• Clitellum only develops during breeding season
• Highly reduced coelom
• Sucker at one end used for locomotion and attachment
to prey
• No chaetae (except one species)
• ½ eat detritus or are predators of small animals
• ½ feed on blood of host
• Salvia has anti-coagulant properties and anesthetics
• Sucks with pharynx
• Time on host varies