Ch 26 Sponges, Cnidarians, and unsegmented worms

Question 1

what is an animal

Answer 1

• heterotrophic
• multi-cellular
• eukaryotic
• lack cell walls

Question 2

what is cell specialization and division of labour within animals

Answer 2

• animals have different cell types that do certain tasks
• division of labour is a phenomena in multicellular organisms where certain cells have specialities or task
• necessary for animals to function

Question 3

what are different types of animal feeding

Answer 3

• herbivores eat plants
• Carnivores eat animals
• omnivores eat a variety of animals and plants
• Parasites feed on living animals and plants in units less than 1
• Filter feeders take tiny organisms from the water
• Detritus feeders eat tiny bits of dead animals and plants

Question 4

how do animals respirate

Answer 4

• All cells need oxygen and give off CO2
• Animals need ways to supply O2 to cells and move Co2 away
• Some use absorption
• Others use various organs

Question 5

how do animals accomplish internal transport

Answer 5

• not necessary In small aquatic animals
• contain O2, nutrients, and waste, which they move to/from cells
• Example: the human circulatory system

Question 6

how do animals excrete waste

Answer 6

• Wastes like ammonia must be eliminated
• small aquatic animals diffuse it out
• Larger animals need a system to remove their poisonous waste products

Question 7

how do animals respond to stimuli

Answer 7

• Animals need to react to stimuli
• Most develop a system of neurons (special cells) called a nervous system to react to stimuli
• some have what we call brains, but there is a lot of variety

Question 8

how do animals move

Answer 8

• most animals move
• tissue called muscles generate force on solid structures (mostly)
• Exoskeletoms
• Endoskeletons
  form the muscle-skeletal system

Question 9

how do animals reproduce

Answer 9

• Many ways to reproduce
• sexual, asexual, sometimes both
• eggs, live birth, other methods
• all young develop, though some have larval forms that metamorphosis into adults

Question 10

what are some trends in animal evolution

Answer 10

• all phyla have a complex family tree of relation
• levels of organization become higher as animals become more complex in form (cells to organ systems)
• many simple animals have radial symmetry, complex ones have bilateral symmetry
• for bilateral animals the front = anterior, back = posterior, top = dorsal, bottom = ventral
• many complex animals concentrate sense organs near the anterior end (head) region, along with nerve cells. This is called cephalisation
• clusters of nerve cells can make decisions and react to stimuli, these are called ganglia and even bigger structures are called brains

Question 11

what are sponges

Answer 11

• The most ancient animals
• appeared 580 million years ago
• live mostly in salt water, some live in fresh
• live in most oceans
• phylum porifera
• don’t move, once thought to be plants
• no mouth or gut
• no specialized tissues or organ systems
• biologists think sponges were an early split that produced no other animals, possible split before they were animals

Question 12

what do sponges look like

Answer 12

• very simple
• a wall formed around an internal cavity
• the wall is very porous and certain cells called collar cells use flagella to pump water into it
• the water exits through a hole called the osculum
• the flow of water delivers food and O2, and moves waste, gametes, and larva out
• Tiny spines called spicules form a skeleton
• cells called amebocytes build spicules from CaCO3 or SiO2
• The softer sponge skeletons are made of fibers called spongins

Question 13

how do sponges reproduce

Answer 13

• sponges filter feed and cells use endocytosis to digest inter cellularly
• sponges pump a large amount of water through its body each day

Question 14

how do sponges reproduce

Answer 14

• sponges release sperm into the water which can eventually reach a sponge where the amebocytes transport it to eggs, eventually the larva are released into the water
• Some freshwater sponges release gemmules, collections of amebocytes surrounded by a layer of spicules which act as spores
• most sponges can also bud to reproduce
• sponges can also reassemble or regenerate when destroyed

Question 15

how do sponges fit into our world

Answer 15

• they are the most common forms of life in dark aquatic places
• other marine animals live on, in, and around them
• they form symbiotic relations with non animal organisms
• a type of sponge called the boring sponge tunnels through old shells and coral, and so help clean up the ocean
• Sponges are used by humans for various things, cleaning, certain chemicals are used, etc
• they produce antibiotic foundations (or antivirals)

Question 16

what is within phylum Cnidaria

Answer 16

• Phylum Cnidaria
• Contain jelly fish, anemones, and others

Question 17

what do Cnidarians look like

Answer 17

• soft bodied organisms with stinging tentacles around a mouth
• most have a two stage lifestyle, with a sessile flowerlike polyp becoming a mobile bell shaped medusa
• their body wall surrounds a gastrovascular cavity where digestion is performed
• the body wall has three layers, the epidermis, mesoglea, and gastroderm
• The Mesoglea is a non-cellular membrane that varies in thickness, many contain amebocytes

Question 18

how do Cnidarians perform their functions

Answer 18

• have stinging structures called nematocysts which catch food
• each nematocyst is a venom filled sac containing a spring loaded dart
• the food item is poisoned, pushed into the cavity, broken down, and diffused into the cells (before being pushed out the mouth/anus opening)
• Cnidarians are heterotrophic but may have symbiotic relationships with photosynthetic lifeforms
• few complicated systems
• have a nerve net instead of a brain
• some have simple sense organs
• no muscles, but they can contract their epidermis
• polyps can bud asexually while medusas have “sex”, produce offspring which become medusas

Question 19

what are hydras and their relatives

Answer 19

• Class Hydrozoa
• Spend majority of their life as polyps
• grow in branching colonies
• specialized polyps do certain functions like feeding or defense
• Hydras are common in fresh water
• they are solitary and lack medusa stages of life
• asexual or sexual
• both separate sexes and hermaphrodite
• are one example of an unusual hydrozoan is the Portuguese man-o-war

Question 20

what are jellyfish

Answer 20

• class Scyphozoa, true jellyfish
• Polyp = larval stage
• Vary a lot, only some are harmful

Question 21

what are sea anemones and corals

Answer 21

• class Anthozoa
• only polyps
• bud or release eggs/sperm into water
• some have symbiotes
• corals produce a CaCO3 skeleton
• Bud to reproduce
• form coral reefs

Question 22

how do cnidarians fit into our world

Answer 22

• lots of symbiosis
• coral reefs form habitats and are very important for marine life
• some have medical implications of their chemicals
• lots of research to be done

Question 23

what are unsegmented worms

Answer 23

• bodies not fully divided into segments
• 2 phyla: Flatworms (Platyhelminthes) and Round worms (Nematoda)

Question 24

what are flatworms

Answer 24

• Platyhelminthes
• Simplest animals with bilateral symmetry
• some have cephalization
• very thin, though can be long or wide
• more developed organ systems than sponges and Cnidarians

Question 25

what are the two forms of flatworms

Answer 25

• 2 very different lifestyles
• Free living, aquatic, flatworms
  
  • Carnivores, predators, or scavengers
  • an opening at the end of a tube is called the pharynx and sucks in food
  • cavity forms long intestines which break down food
  • food is diffused and waste expelled through mouth
• Parasitic flatworms
  
  • drink blood, or inhabit host
  • ex: tapeworms
  • many don’t have stomachs and just absorb pre-digested food from the host

Question 26

what is the form and functions of flatworms

Answer 26

• Flatworms have no circulatory or respiratory systems
• some fresh water flatworms have cells called flame cells that get rid of excess water
• free living flatworms have developed nervous systems, simple brains, nerve cords, and light sensitive ocelli (or eyespots) that can see shadows
• Parasitic Flatworms have less nerves
• Free living flatworms use cilia on epidermal cells or have muscle cells that allow twisting
• Free living flatworms reproduce with both hermaphroditic sex or asexually via fission
• parasitic reproduce sexually in complex lifecycles

Question 27

what are planarias

Answer 27

• class turbellaria
• free living flat worms
• vary a lot, the biggest are 60 cm long

Question 28

what are flukes

Answer 28

• class Trematoda
• parasites
• live in and on hosts, lost of damage
• many infect humans

Question 29

what are blood flukes

Answer 29

• Blood flukes are found in SE Asia, N Africa, and other tropical regions
  
  • they live in blood
  • the genus Schistosoma use humans as hosts
  • many flukes reproduce as hermaphrodites (with individuals producing eggs + sperm)
  • Schistosoma have separate sexes, they release many eggs into blood vessels, which burst and leak into the intestines, pooped out, and sometimes go into water where they hatch into larva, the larva then enter a snail, grow, and eventually find a new human host
  • Human flukes can be very dangerous
  • non human flukes can infect humans, but only cause swimmers itch

Question 30

what are tapeworms

Answer 30

• class Cestoda
• simple parasites
• have a head with hooks called a scolex
• they attach to the intestine and absorb food
• can be over 15 m long
• usually don’t kill, but eat a lot
• behind the scolex is a neck part that divides to make proglottids or sections that extend the body and contain reproductive eggs in the later sections
• eggs fertilize and drop off with the back proglottids
• tapeworms can inhabit muscles of intermedial hosts and form a cyst

Question 31

what are round worms

Answer 31

• phylum Nematoda
• Simplest animals to have 2 digestive openings, a mouth and an anus
• vary in length up to 10 meters
• many around us at all times, 90 000+ in a rotting apple

Question 32

where can round worms be found

Answer 32

• mostly free living
• found all across earth
• some parasites, in nearly every kind of plant and animal

Question 33

how do round worms perform life functions

Answer 33

• long tube shaped digestive tract
• free living are carnivores for the most part
• some have other diets
• parasitic damage to lots of crops
• excrete waste through body walls
• simple nervous system, less than flatworms, no brain, only ganglia
• muscles strips allow movement
• all ways reproduce sexually, internal fertilization
• some parasitic roundworms have 2-3 hosts, others spend time in multiple different organs

Question 34

what is ascaris

Answer 34

Ascaris affects humans, they live in the intestines where the produce eggs, when the eggs are consumed larva hatch, burrow into blood vessels of small intestines, entre the blood stream, go to lungs, climb to throat, get swallowed and end up in the intestine once again

Question 35

how do unsegmented worms fit into our world

Answer 35

• little effect on humans aside from some parasites
• hook worms, found in the USA, are similar to ascaris
• Trichinosis is caused by worms called trichinella which burrow into organs to cause pain
• Filarial worms are found in the tropics of Asia and cause Elephantiasis
• Eye worms burrow below the skin and can be seen crossing the eye on occasion