Cnidarians
Describe the five characteristics shared by cnidarians.
Radial symmetry
Diploblastic organization
Nematocysts
Polymorphism
Nerve net
Name 3-5 characteristics that make up Porifera.
What was Charles Darwin's contribution to science? What did he publish?
Developed natural selection; supported common ancestry; published On the Origin of Species in 1859.
Describe the difference between systematics and taxonomy.
Systematics - Study of biological diversity and evolutionary relationships; asks “How are organisms related?”
Taxonomy - Science of naming and organizing organisms; asks how we name and organize them.
Define embryology.
Embryology is the study of development of a fertilized egg until all major organ systems have formed.
Describe diploblastic organization - what layers are involved? What do they form? What layer is missing and what exists in its place?
Layer/structure
Ectoderm → epidermis - Outer body layer.
Endoderm → gastrodermis - Lines the gastrovascular cavity.
Mesoglea - Jelly-like layer between them; cnidarians have no mesoderm.
How does sexual vs axexual reproduction occur in sponges? Describe both processes. What is the pro and con of each?
Sexual reproduction: Most sponges are monecious but generally don't self-fertilize, so sperm flows through water, enters another sponge, and is transported to an egg in the mesohyl. Fertilization produces a zygote which develops into a motile larva, which swims away and settles on substrate to develop into a sessile adult. Pro is genetic diversity, con is more energy used.
Asexual reproduction: Budding, a new sponge grows from the parent, breaks free, settles and grows. This leads to identical clones, which is less genetic diversity, but takes up less energy.
Describe who Geore-Louis Leclerc was and what a vestigial structure is.
His focus was on comparative anatomy, vestigial structures, and the idea that species might change. Vestigial structures are a body part or organ that has lost most or all of its original function through the course of evolution.
Kingdom, phylum, class, order, family, genus, species.
What is cleavage? Describe the process and what occurs.
The embryo undergoes repeated mitotic divisions but does NOT substantially increase in overall size. The blastomeres become progressively smaller.
Describe the function of cnidocytes and nematocysts and how they are beneficial in Cnidaria.
A cnidocyte is a specialized stinging cell. It contains a nematocyst—a coiled, hollow thread/capsule.
Functions: feeding, defense, and anchoring.
Sequence: stimulus/contact → nematocyst fires → thread penetrates or entangles prey → prey is captured.
Nematocysts solve the prey-capture problem for animals without jaws or claws.
Describe a gemmule. What is the purpose of producing one? What do they contain? What happens after a gemmule is formed?
Some sponges produce gemmules—resistant capsules containing archaeocytes. They can survive freezing, drying, and unfavorable conditions. When conditions improve, archaeocytes emerge, cells reorganize, and a new sponge forms.
Who was Jean Baptiste Lamarck? What was his contribution? Was it disproved or proved and by who?
Lamarck proposed that acquired changes could be inherited. The lecture uses the example of a person developing larger muscles through exercise and asks whether their children would automatically inherit those larger muscles.
Weismann repeatedly cut the tails off mice and allowed them to reproduce for more than 20 generations. Every generation was born with normal-length tails; offspring did not inherit the shortened tails. Therefore, the experiment failed to support Lamarck’s hypothesis.
Which scientist was responsible for coming up with our current system for naming organisms? What is this system called? What are the components that go into naming a species?
Carolus Linnaeus developed binomial nomenclature, a system for naming organisms. Each species receives a two-part scientific name:
Example: Baeolophus bicolor
What are the three gastrula regions and their functions?
Coelomic pouches - Body cavity
Archenteron - “Primitive gut” / digestive tract
Blastopore - Opening of the gut
Tell me about the four jellyfish classes from the lecture, and an identifying characteristic of each.
Hydrozoa – hydra, obelia, Portuguese man of war. Has a velum and are often colonial.
Scyphozoa – true jellyfish. Lacks a velum.
Cubozoan – box jellies. Has a velarium and potent venom.
Anthozoa – corals and sea anemones. No medusa, only polyp.
Compare and contrast the three sponge body plans. How are they different? What makes certain ones more efficient and less efficient?
Ascon - Simple vase-like body; spongocoel has no folds; small choanocyte surface area; generally small. Less surface area.
Sycon - Body wall becomes folded. More surface area → more choanocytes → greater feeding capacity.
Leucon - Extensively branched canals and many choanocyte-lined spaces; greatest surface area. Can support a larger body size.
Who was Charles Lyell? What was his contribution, and what did it indicate? What questions came of this?
Principles of geology, the idea that the same geological processes we observe happening today also operated in the earth’s past, and small changes accumulating over immense time can produce major change. So the earth was deemed older than 6000 years after all.
Name the five pieces of evidence used to determine relatedness, or describe the two patterns in which evolution may proceed.
Gradualism - Slow, continuous change; small differences accumulate over long periods.
Punctuated equilibrium - Long periods of little change interrupted by relatively rapid evolutionary change.
What is the sequence of early development in order?
Unfertilized ovum, fertilized ovum, 8-cell stage (may also include 16-cell, 32-cell), morula, blastula, early gastrula, and late gastrula.
Diagram or draw the life cycle of aurelia, and explain what happens in each stage.
Should include an adult medusa, followed by spermatozoa/egg, planula, scyphistoma, young strobila, strobila, young medusa (ephyra) and back to adult medusa.
Draw a sponge body plan of your choice and label its parts (don't forget specific cells and their functions, skeletal system, etc!)
Parts identified may include microvilli collar, choanocytes with flagella (more in folded walls = greater ability to collect food), spongocoel, ostia, osculum, pinococytes, mesohyl w/archaeocytes, spicules, spongin. The diagram should show water flow through the ostia and out the osculum.
Specifics on each part in my notes app.
What are the four observations behind natural selection? What is the core idea?
1. Overproduction - More offspring are produced than survive.
2. Variation - Individuals in a population differ.
3. Heritability + differential success - Some inherited traits improve survival and/or reproduction in a particular environment.
4. Change across generations - Individuals with advantageous traits leave more offspring, so those traits become more common.
Core idea: individuals are selected, but populations evolve. Evolution is a change in inherited characteristics of a population across generations.
Describe (or draw) all the components of a phylogeny. What is the anatomy of a phylogenetic tree? What does each part indicate?
Phylogeny - Evolutionary relationships among organisms.
Tips - Taxa.
Branches - Lineages.
Nodes - Common ancestors.
Clade - One common ancestor plus all of its descendants.
Shared derived characteristics - Can help identify clades.
Explain how germ layers are produced, organized, and what the germ layers form.
Should explain that the tissue of a blastula folds inward to form the gastrula with the opening known as a blastopore, and the gastrula forms the three germ layers: Ectoderm (outer body/nervous system), Mesoderm (muscles, blood, skeletal, reproductive), and Endoderm (inner lining of digestive and respiratory)