Why is there segmentation in Arthropods AND Annelids?
If annelids were actually closely related to Arthropoda then that means that either segmentation was lost independently in a bunch of Lophotrochozoans or segmentation evolved independently in annelids and arthropods.
Four Main taxa of Arthropoda
Be able to draw tree with Porifera, Cnidaria, Platyhelminthes, annelidia, molluska, lophotrochozoan, edysozoan, protostomes, deuterostomes, chordata and echinoderms
Crustacea+ Hexapoda =
Myriapoda + Pan crustacea =
Which of the four insect orders dominate life on earth, and what are two things that they have in common.
Can you name some extinct arthropod taxa? To which phylum do they belong?
Can you name some of the distinctive advantages of arthropods that may have influenced why there are so many of them?
What are the synapomorphies for Arthropoda?
Where did arthropod mouthparts come from? What did the hypothetical arthropod ancestor look like?
Where did segmentation come from?
Segmentation evolved from mutation, (as does everything). A duplication of regulatory genes (HOX).
specialization grouped by body region
If all segments are serially homologous, are they all the same?
How are segments specialized?
What are the different tagmata specialized for?
What is cephalization?
the specialization of the anterior end as a center for neural integration, sensory reception, food capture. Its not just turning legs into mouthparts and antennae, it is also the consolidation of nerves into ganglia.
How many tagmata do Chelicerates have?
It is the result of the fusion of multiple segments, and that the boundaries of these ancestral segments are no longer visible.
Spiders, mites, ticks, scoprians, daddy long legs
Eurypterids were dominant predators of what era? When was it?
Eurypterids were in what class/sub phylum?
Explain Xiphosura synchronized mating? How does it influence bird life?
What is special about horseshoe crab blood?
Why are Horseshoe crabs declineing?
Harvested without restriction (fish bait and fertilizer)
Label a Horseshoe crab.
What do Pycnogonidas eat?
Suck up soft food with pharynx in proboscis
Some suck juices and others shred first with chelicerae
What chelicerates can eat solid food?
What are these parts of sea spiders for?
1. Eye tubercule?
How do sea spiders care for their eggs?
Mites and ticks
Daddy long legs
How do arachnids eat? chew?
Spiders are divided into how many orders?
What are they defined by?
2 (Mesothelae and Opisthothelae)
Mesothelae is is considered sister taxon to rest
Opisthothelae splits again and is defined by fag orentation
Opisthothelae (spiders) is split into two groups. Describe them and give examples.
One group (Mygalomorphae) is the primative one in which the fangs point toward the ground and do not cross each other. Includes trantulas.
The other group (Araneomorphae) is a groups of spiders (most of them) in which the chelicerae meet and cross each other.
Orb webs are not an ancestral characteristic of spiders but a _____ one
What are brown recluse spiders? Black widows? Tarantulas? Are they dangerous?
What is a crustacean exoskeleton made of?
The exoskeletons of insects and crustaceans is different why? how are they the same?
In what ways do insects and crustaceans differ?
1. Respiratory - insects use trachea, crustaceans use external gills
3. Exoskeleton- different ratios of CaCO3 and Chitin
4. Antennae- Insects have 1 pair, crustaceans have 2
What are the defining characteristics of Crustaceans?
2 pairs of antennae
Complex three part brain (tripartite)
What are Biramous appendages?
A biramous appendage is one that has two branches. Crustacean biramous appendages have a basal or first portion referred to as the protopod. (Proto means first or early, like prototype, and pod means foot, so protopodite means the first part of the foot). As you move away from the body on a biramous appendage you find a branch on the outside, the exopod (exo means outer), and a branch on the inside, the endopod (endo means inner)
Explain the Crustacean body plan
Head- 6 segments that fused
Explain regional specialization
Appendages of different segments have different fom and function because of specialization
Propodus is can not flex, Dactyl can flex, carpus is the "wrist"
Feeding methods of smaller crustaceans. How do larger crustaceans differ?
Use biramous appendages (rami) to stir particles from the bottom.
The protopod is a gnathobase with teeth.
Particles enter food groove where gnathobases grind the food and move it to mouth.
Gut is J-shaped
Mouth points posteriorly toward food groove
Particles are so small they do not require grinding.
Larger crustaceans differ becausr they contain gastric mill in the stomach (contains circular teeth)
Reproduction of Crustaceans
Most are gonochoristic (few barncles are hermaphrodites)
Internal fetilization and copulation
Many types of sperm transfer
Eggs brooded by females on or in a variety of structures
Indirect development in Crustacea
Egg hatches as a larva unlike the adult. Larva must undergo a series of molts to add segments and appendages until it becomes an adult.
Direct development in Crustacea
Embryo remains in the egg until it has all segments and appendages and then it hatches
It resembles the adult
A type of crustacean larva that is planktonic and has thre pairs of appendages. Use antennae to swim.
Crustacean larva that swims using its thoracic appendages
Remipedia are a groupd of crustaceans that a cave dwelling crustaceans and are closely related to Arthropods
What are Cehalocarida?
Small group of crustaceans that live in the mud, have4 no eyes and were discovered in 1955.
What is Vericrustacea? Why is this group important?
Vericrustacea is the taxa that includes the typical crustaceans
Includes orders Phyllocarida, Notostaca, Thecostraca, Anostraca, Copepoda, and Decapoda.
What is important about the order Notostaca (shrimps)?
In the class Brachiopoda
Includes Triops (living fossil)
Anostraca (brine shrimp) + Notostraca (triops) =
Triops are called living fossils because?
Unchanged for many years.
Similary to trilobites
Triops and Brine shrimp aren't related. T or F?
False, they are closely related.
What is a relictual habitat?
An enviornment that goes under a considerable amount of change.
Examples: glacial lakes, salt lakes and groundwater
The group cladocera (water fleas) is important because they have cyclical parthenogensis. Desribe what cyclical parthenogenisis is.
A form of asexual reproduction in which growth and development of embryos occur without fertilization. Lay 4-10 eggs per clutch. Clutch carried i brood pouch until next molt (hatching).
Why is sexual reproduced eggs important for Caldera (sea fleas)? Why is parthenogenisis important?
Live in isolated unstable enviornments. Eggs are resistant to desiccation and temperature extremes and only hatch when conditions are optimal.
Parthenogenesis works great because after sex eggs hatch, parthenogenesis can ramp up large numbers quickly.
What is Cycloorphosis?
Seasonal morphological change in successive generations without change in genome. (change in phenotype)
Triggered by temperature change, turbulence, photoperiod, food and presence of predators.
Decopods, Phylocardia and Mantis shrimp are part of a larger group called _______.
Arguably ... contains a greater diversity of body forms than any other class in the animal kingdom
Includes largest crustaceans (shrimp, lobsters, crabs, krill, etc.)
Tagmata: Head is 5, thorax is 8, abdomen is 6
Tongue worms and fish lice are parasitic. Where do they live?
Fish lice: On the perculum of a bony fish (the hard bony flap covering and protecting the gills).
Tongue worms: Respiratory tracts of vertebrates
Ostracoda (Seed Shrimp) is a class is crustacea. What do they look like?
Tiny crustaceans with a hinged bivalve carapace.
What is closely related to a remipede a beetle or a lobster?
Why are there so many insects?
1. Size - small size promotes speciation because they can divide habitats into microhabitats
2. Metamorphisis- allows larva to fill one niche and adults to fill another
3. Wings- create a 3D niche
Pterygota is a taxa in Hexapoda. What does Pterygota mean?
Neopteran is a taxa in Hexapoda. What does Neoptera mean?
Holomethabola is a taxa in Hexapoda. What does it mean?
Complete metamorphisis. Think cacoon.
The three ancestrally wingless taxa of Hexapoda are Collembola, protura, and Diplura. Are they insects? What is there enviorment like?
Restricted to leaf litter
Which two groups conquered terrestrial life?
Insecta and Amniota
The biggest morphological innovation to ever hit animal ife is Wings. Why are they a sucess?
1. Increased dispersal ability
2. Access new resources
3. Unprecedented ability to es cape predators.
4. Spacial complexity- move from 2D to 3D
What are the advatages and disadvantages of impermeable tegument?
What polysccharide makes up exoskeleton of insects? (cross-linked proteins)
Modified appendages in insects?
Mouthparts are modified legs- different insect ordershave different modifications
Thorax segments? Wings are attached where?
Wings attached to meta and meso
Each has a pair of legs
What are cerci?
Appendages on the last abdominal segment
Hemiptera is a group of in Hexapod. What are they? What special mouthpart do they possess? describe it.
Stylet - has two grooves, one for sucking and one for discharging saliva
Gas exchange in insects
Trachea branches into sclerotized tubes and continues to branch down to microscopic diameters.
Virtually every ell in an insects body is either touching or in very close proximity of these air tubes (tracheoles).
Held open by rings called taenidia
What are spriacles?
Openings in gas exchange system of Hexapods.
Usually valved to prevent moisture loss and control air flow.
Is the tracheal system of insects shed when the molt?
Yes, but tracheoles are not.
invagination of the insect integument
Surface area and gas exchange in insects
Movement of the wings and body parts helps to pump the hemolymph, but the surface area where the oxygenated fluid meets the depleted fluid is limited compared to the volume of fluid
If they were larger, they would not be able to respire.
Insects excrete Uric Acid. Why is this an advantage?
What do marine animals excrete? Why?
Uric acid conserves water while excreting ammonia does not.
Marine animals excrete ammonia. - can easily be diluted in ocean
How do insects conserve water?
Water-tight integument and by excreting uric acid.
Malpighian Tubules in insects
Help produce Uric Acid
Free floating tubes in body cavity
Compound eyes and Ocelli eyes- how do they differ? what do they do?
Compound- can see towards from and sides at same time. Form an image that is processed in brain
Ocelli- detect light. show shadows of predator.
Sperm- delivered in packets internally with a penis. Females can store sperm packets from multiple males.
Males can have adaptation that allows them to remove previous mates sperm packets and can seal vagina.
Males want to father lots of children, females evolved to select good mates
Reasons for tandem mating
No other male can mate with this female as long as the male remains attach
He will remain attached until she lays eggs
Males want to be the only father
Females like to shop around to increase their fitness
Both sexes benefit from multiple mates by mixing genes
What is Hemimetaboly?
Juviniles (nymphs) look like mini adults
Do not pupate or form cocoons
Wings occur when hit adult hood and they never molt again
What is Holometabolous?
Pupa and larval stage - cacoon
Complete reorganization of body plan
Metamorphisis and molthing under harmonal control
1. Competition with adult- Caterpillar eating leaves does not compete with a butterfly eating nectar. This explanation is often invoked, and while it may be true, it may often be an overstated a-posteriori explanation.
2. Eat and hide well- Perhaps even more important is that Holometabolous larvae can be modified to be good at eating and hiding, while adults can more or less independently evolve to disperse and mate. The complete re-design of each stage allows for custom fitting into each role.
3. Diapause and/or the pupal stage allow insects to sit out unfavorable conditions, again increasing the number of habitats they can colonize.
4. Odonata, Ephemeroptera, Plecoptera “cheat” by having aquatic larvae. Some data show that orthopterans (acridid grasshoppers) may not compete for food, but this may have something to do with their extreme mobility. So some highly mobile species may be able to act as if they were holometabolous.
Juvinelle harmones ?
Used to control mosquito population
One mimics another one that is not edible
coefficient of relatedness in eusociality
Pick a gene in one offspring, and there is a 75% probability that if you picked another offspring it will have the same copy of that gene.
Occasionally a gene for being selfish may arise, but it won’t spread for a couple of reasons:
1) Offspring have only 50% probability of caring that gene. Sisters are closer relatives than children.
2) Selfishness is often punished by death, thereby removing that gene. So this is a system where taking care of your sisters actually results in the spread of your own genes.