Chapter 20 - Biodiversity of Invertebrates Flashcards
What is an invertebrate?
Any animal without a backbone.
What is an animal? What are their main characteristics?
Multicellular eukaryotes that are heterotrophic and usually ingest food (through a mouth). No cell walls.
What is the basic animal life-cycle (7 steps)?
- Gametes via meiosis, 2. zygote (2n), 3. zygote divides, 4. blastula stage, 5. gastrula stage, 6. some have a larval stage before metamorphosing into 7. an adult.
What is the blastula stage?
A stage of the animal life cycle when the organism is a hollow ball of cells.
What is the gastrula stage?
A stage of the animal life cycle when the hollow ball of cells from the blastula stage folds in on itself creating the ecto- and endoderm.
What are the three layers of tissues that embryonic animals have? What part of the adult animal do they become?
- Ectoderm - outer layer, becomes skin etc. and nervous tissue.
- Endoderm – inner layer, becomes the digestive tract lining.
- Mesoderm – the middle layer (most, but not all, have this), becomes muscles and most internal organs.
When do we think the lineage to animals occurred? When are the earliest animal fossils from?
1 bya.
Earliest fossils are from 575-550 mya.
When was the Cambrian period? Why was there an explosion of animal life then?
535-525 mya.
Perhaps due to increasingly complex predator-prey relationships, an increase in atmospheric oxygen, or warmer temperatures.
What things do we look at when describing and categorizing animals?
Body symmetry, do they have 2 or 3 tissue layers, what those layers develop into, whether the opening in the gastrula becomes the mouth or the anus, and type of body cavity.
What is a protostome? What is a deuterostome?
Animals where the opening in the gastrula turns into the mouth (protostome) or the anus (deuterostome).
What’s the difference between radial and bilateral symmetry?
Radial: primitive animals with a body plan that radiates from a centre with a top/bottom but no left/right
Bilateral: higher animals with a distinct left and right.
What embryonic tissue layers do all animals have and what’s an additional tissue that most animals have?
More primitive animals only have endoderm and ectoderm.
Most also have mesoderm.
What is coelom?
A fluid filled space between the digestive tract and outer body wall. A body cavity that animals with 3 tissue layers can have.
What is a true coelom?
The coelomic cavity (body cavity) is lined on both sides by mesoderm.
What is a pseudocoelom?
The coelomic cavity (body cavity) is only lined on one side by mesoderm tissue.
What are acoeolomate animals?
Animals with no coelomic cavity (body cavity) at all.
What are Porifera? Where do they rank in the complexity of animals?
The sponges! The simplest, most primitive animals. Not really considered “true” animals or eumetazoans.
What is a sessile animal?
Permanently attached to a surface; not free-moving.
Why are sponges considered primitive?
No true tissues, no real symmetry, no coelom, sessile, more like a colony of protists than a true animal.
What is the structure of a sponge’s body like? How do they feed?
An inner layer of collar cells and amoeboid cells. Collared cells called choanocytes have flagella to make a current in the sponge. Water flows through and out the excurrent pore. All sponges are filter feeders.
What are Cnidarians, their basic characteristics and some examples?
Aquatic invertebrates. Radial symmetry, two tissue layers, sessile (coral or anemones) or free floating (jellyfish). Carnivores with tentacles. Incomplete digestive tract (only a mouth). No body cavity. Cnidocytes (stinging cells) for defence and prey.
What are Platyhelminthes and their basic characteristics?
Flatworms! Bilateral symmetry, three tissue layers, but no coelomic cavity (acoelomates), incomplete digestive tract. Can be free-living or parasitic.
What are Gastrotricha and their basic characteristics?
Gastrotrichs a.k.a. hairybacks. Microscopic animals with 3 tissue layers, bilateral symmetry, a complete digestive tract, and a pseudocoelom.
What are Rotifers and their basic characteristics?
Tiny multicellular organisms. Bilaterally symmetrical, have 3 tissue layers, a complete digestive tract, a pseudocoelom, a hydrostatic skeleton, and organs.
What is parthenogenesis? Which animals use this method?
A process used by some Rotifers to produce diploid eggs that do not need to be fertilized and become female adults.
What happens when Rotifer’s haploid eggs are fertilized or unfertilized?
Fertilized eggs become females that can produce diploid eggs. Unfertilized haploid eggs will develop into males.
Do Rotifers reproduce sexually or asexually? Why?
Both! Asexually when the environment is stable. Sexually when things are unpredictable (like in the fall).
What are Nematodes and their basic characteristics?
Roundworms! Bilaterally symmetrical, have 3 tissue layers, have a pseudocoelom and complete digestive tract. Are decomposers and parasites.
What is a complete digestive tract? What is an incomplete digestive tract?
A digestive system with a separate entrance and exit. Incomplete has only one opening.
What are Tardigrada and their basic characteristics?
Water bears or moss piglets!
Bilateral symmetry, a complete digestive system, 3 tissue layers, mostly a pseudocoelom, though a partial true coelom. Super tough.
What is cryptobiosis? Which animals do this? What can they withstand when they are in the tun state?
When Tardigrada pull in their head and legs, lose 97-99% of their water and go into a state of suspended animation. Metabolic rate 0.01% of normal. Become basically lifeless. Can withstand 0 water, extreme temps and radiation, and even the vacuum of space!
What are Mollusca and their basic characteristics?
Molluscs (snail, slugs, clams, octopus)
Soft-bodied, many have shells, 3 tissue layers, a true coelom, complete digestive tract AND circulatory systems, primitive hearts and kidneys, gonads and gills.
What is the basic body plan of a mollusc?
A foot (to move), a visceral mass (w/ internal organs) and a mantle (tissue covering the visceral mass, and secretes the shell)
What are the three basic groups of molluscs with examples?
Gastropods (belly-foot; snails, slugs), bivalves (double-valved; clams, oysters, mussels, scallops), and cephalopods (head-foot; octopus, squid, nautilus, cuttlefish).
How intelligent is an octopus? What are some of the things they can do? How long do they live?
Very, considered the most intelligent invertebrates. Escape aquariums and tanks, open jars, disassemble their tank’s plumbing, turn off lights, use tools, camouflage, strangle sharks, take pictures!
2 years or less.
What are annelids and their basic characteristics?
Segmented worms with repeating body units in each segment. Bilaterally symmetrical, 3 tissue
layers, a true coelom, primitive hearts (kinda made of blood vessels).
What are the 3 main groups of annelids?
Earthworms, polychaetes (Free-living, marine annelids), and leeches.
Which types of invertebrates have primitive organs?
Molluscs and annelids.
What type of circulatory system do most invertebrates have?
An open circulatory system in which blood is pumped through vessels that open into body cavities.
What type of circulatory system do most vertebrates (and annelids) have?
A closed circulatory system where blood remains enclosed in vessels as it distributes nutrients and oxygen throughout the body.
What are hermaphrodites? Which animals are an example of this?
Animals with both male and female
reproductive structures, but they don’t self-fertilize.
Earthworms.
What is a hydrostatic skeleton?
A type of skeleton supported by hydrostatic fluid pressure or liquid. No bones or exoskeleton needed!
What are Arthropoda and their basic characteristics?
Arthro = jointed, poda = foot. Segmented animals with jointed appendages and chitinous exoskeletons. Bilaterally symmetrical, 3 tissue layers, a true coelom, they moult!
How big is the phylum Arthropoda? What are some examples of these animals?
By far the largest phylum in the animal kingdom. Includes crabs, lobsters, crayfish, barnacles, spiders, ticks, mites, insects, millipedes, centipedes.
What are the different groups of arthropods (5)?
- The Chelicerates (horsehoe crab).
- The Arachnids (scorpions, spiders, ticks, mites).
- Millipedes and Centipedes.
- Crustaceans (lobsters, crayfish, barnacles, crabs, and shrimps.)
- Insects (most successful group)
How many insect species have been identified? What percentage of animal species is this? Where do they usually live?
More than 1,000,000.
Insects make up over 70% of known animal species.
Some on land, many in freshwater, but not many in the oceans.
What stage of the live cycle is dominant in many insects?
Larval forms.
What is the benefit of having a larval stage that lives in a different environment from the adult stage?
They have different ecological niches and food sources to limit intergenerational competition.
What is the sole function of the adult stage for many insects?
The adults often function solely for sexual reproduction and dispersion.
What’s the difference between complete and incomplete metamorphosis?
Complete = larva, pupa, and adult.
Incomplete = larva to adult without a pupal stage.
What are the main body parts of an insect (3)?
Head, thorax (usually w/ 3 pairs of legs and wings), abdomen.
What are some incredible adaptations in certain insects?
Amazing camouflage to look like sicks, leaves, and bird poop.
Which animal kills the most people every year and how? How many people do they kill?
Mosquitoes! (nasty mothersuckers) By transmitting diseases.
725,000 deaths per year.
What disease do some mosquitoes in Winnipeg spread? Who is most affected by this.
West Nile Virus.
People with chronic diseases and weakened immune systems are at greatest risk.
How do mosquitoes find their victims? From what distance can they find victims? Do males bite?
Smell using chemoreceptors
in their antennae. They can sense CO2 and chemicals found in perspiration from 6-27m away.
Only females bite.
What is the basic mosquito life cycle? How long does it take?
Egg (1-2 days), larva (4-6 days), pupa (a few days), adult (only stage out of water). The entire cycle can take less than 10 days.
Males hatch first and “listen” for females of their species.
How long have dragon flies existed? What are some amazing features they have?
300 mya. Their eyes have up to 25,000 lenses, can see 360 degrees, spot mosquitoes 20 m away, fly 50 kph, 90 degree turn at full speed.
What is the basic dragonfly life cycle?
Eggs laid in water; larva (nymph for 1-3 years) voracious predators in water; moults into an adult (voracious predators in air, living a few weeks to months).
What are Echinoderms and their basic characteristics?
Echino = spiny, derm = skin. Sea stars, sand dollars and sea urchins. Adults have radial symmetry but larvae have bilateral symmetry, first deuterostomes, endoskeletons.
What do echinoderms and chordates have in common (2)?
They are bilateral animals and deuterostomes.
What is a protostome vs. a deuterostome? Which invertebrates are protostomes?
Proto: The mouth forms before the anus during embryonic development.
Deutero: bilaterian animals that form the anus before the mouth during embryonic development.
All except echinoderms are proto.
What are chordata?
A phylum including all vertebrate animals and some invertebrates – such as the tunicates and the lancelets.
What are the 4 main characteristics that all chordates have?
- A dorsal hollow nerve cord (hence the name);
- A notochord (a supportive rod between the digestive tract and the nerve cord);
- Pharyngeal slits;
- Muscular post-anal tail.
Do all chordates have vertebrae?
No, the first chordates do not have vertebrae (tunicates and lancelets and hagfishes).
Are all vertebrates chordates?
Yes, but not all chordates are vertebrates.
