Animals II: Protostomia: Lophotrochozoa and Ecdysozoa Flashcards
What are Bilaterians
All animals except Cnidarians, Porifera, and Ctenophora are grouped into a group called the Bilaterians which arose between 680-670 BYA
All Bilaterians have 3 true tissues, and are bilaterally symmetrical
How is Bilateria divided
It is further divided into 2 groups
Deuterostomes: Hemichordates, Echinoderms, and Chordates
Protostomes: Platyhelminthes, Rotifera, Ectoprocta, Brachiopoda, Mollusca, Annelia, Nematoda, Arthropoda
there is also Acoela which is outside the two groups
What are the two clades of Protostomes
Of Protostomes there are 2 clades:
- Lophotrochozoa: Platyhelmintheses, Rotifera, Ectoprocta, Brachiopoda, Mollusca, Annelida
- Ecdysozoa: Nematod, Arthropoda
What are Lophotrochozoans
some Lophotrochozoans have a feeding structure called a lophophore. (Lopho = crest)
while others have a distinct stage called a trochophore larva
(Trocho = wheel)
What are the 3 main groups of Lophotrochozoa
3 main groups represent Lophotrochozoa:
- platyhelminthes: Flatworms
- Annelida: Segmented worms
- Mollusca: Mollusks
What are Platyhelminthes
Flatworms
Flatworms have free-living and parasitic species
examples include Planaria (adorable little things) Flukes (which cause swimmer’s itch and a bunch of diseases) and tapeworms (which are tapeworms)
Have a flattened unsegmented body
No Coelom
Open circulatory system
What are Annelids
Segmented worms
Annelids have a cylindrical and segmented body with a Coelom and Closed Circulatory system
What are the two main groups of Annelids
Annelids include two main groups
- Errantia includes bristle worms, pileworms, scalewormsThey are relatively mobile, many are jawed and predaceous
- Sedentaria includes tubeworms, earthworms, and leechesThey are relatively immobile (sedentary)
What are the two types of circulatory system
- Open circulatory systems involve a heart pumping a blood like substance Hemolymph through tubes onto various organs, it exists blood vessels and is taken back into the heart. Hemolymph in sinuses surrounding organs
- Closed circulatory systems involve a heart pumping blood through a series of branching blood vessels which exchange materials with cells. Outside the Vessels is interstitial fluid
What is Mollusca
Mollusca includes several groups such as
Gastropoda: Conchs, whelks, winkles, sea slugs, slugs, limpets, snails
Bivalvia: clams, mussels, Oysters
Polyplacophora: Chitons
Cephalopoda: Squids, Octopuses, Cuttlefish, Nautiluses
Describe Mollusk anatomy
- Molluscs have 3 main parts
- Visceral mass, which is most organs
- Mantle, the protective top bit
- Foot, bottom bit, allows movement
- Aside from Cephalopods they have open circulatory systems
- and the have a Coelom
What is Ecdysozoa
Ecdysozoa includes all Invertebrates which shed their Exoskeleton during growth in the process of Ecdysis (molting)
Includes Nematoda (25,000 species) and Arthropoda (1,000,000 species), along with smaller groups like Loricifera (10 species), Priapula (16 species) Tardigrada (800 species), Onychophora (110 species)
What are Nematods
Also known as Round worms
They are unsegmented worms with a flexible exoskeleton
They don’t have a true coelom or circulatory system
They live mostly in Aquatic areas or moist soils; some are important parasites of plants and animals
What are Arthropods
Arthropods are an immensely diverse group of Invertebrates
Includes Chelicerates, Myriapodes, Hexapods, and Crustaceans
Describe Arthropod anatomy
They have a segmented body with rigid exoskeletons that are highly modified for:
- protection against physical damage
- Water retention
- locomotion
- feeding and defence (claws and stingers)
- Sensory organs (antennae)
- reproduction (external genitalia)
Arthropods possess a reduced coelom and an open circulatory system in which hemolymph is circulated into the spaces surrounding tissues and organs by a heart
A variety of organs were specialized for gas exchange in arthropod evolution
What are Protostomes
Protostomia includes Lophotrochoza (Flatworms, segmented worms, and Mollusks) and Ecdysozoa (Arthropods and roundworms)
Flatworms, Annelids, Mollusks, and Arthropods are all protostomes along with round worms, velvet worms, ribbon worms, Bryozoans, brachiopods, rotifers, priapulans, Loriciferans, and Tardigrades
They all have three true tissues, and are bilateral
What is the difference between Protostomes and Deuterostomes
In Protostomes the mouth develops from the blastopore before the anus
In deuterostomes the anus develops from the blastopore before the mouth
What does Lophotrochozoans
Lophotrochozoans contains Platyhelminthes, rotifera, ectoprocta, brachiopoda, mollusca, and Annelids
What are Coeloms and Hemocoels
A Coelom is just a cavity that holds the organs and stuff
a Hemocoel is a Pseudocoelom which is a cavity containing the digestive tract, it is not a true coelom but convergently evolved with it
What are Gastropods
Gastropods include conches, whelks, winkles, slugs, limpets, snails, etc
- they are slow moving
- name means stomach foot
- most have conical shells, some have no shells
What are Bivalvia
Bivalvia includes clams, mussels, oysters
- are sessile
- have paired shells
- perform suspension feeding
What are Polyplacophores
Polyplacophora includes chitons
- shell made of 8 plates/valves
- slow moving
- grazers
What are Cephalopodes
Cephalopoda includes squids, octopi, cuttlefish, and nautiluses
- closed circulatory system
- shell typically absent
- fast moving
- predators
- most complex well-developed brains and eyes among invertebrates
What is up with cephalopod shells
- Typically absent
- Squid do have an internal “shell”
- Nautilus have a shell with internal “septa”
- Their common ancestor likely had a shell, looked something like a Monoplacopheran
what is up with mollusk larva vs adults
Larva are cephalized, adults are more or less bilaterial
What happened to shelled cephalopods
- Shelled Cephalopods dominated the oceans until mass extinctions wiped them out before the cretaceous
- ~17,000 extinct species, 800 extant
- Most important groups of past have no descendants
What are Flatworms
- Flatworms = Platyhelminthes
- mouth on bottom around the centre
- no Coelem
What defines Ecdysozoa
Arthropods and Nematods
they molt during growth
Nematodes have a more flexible exoskeleton, but they still molt
Arthropods have a harder exoskeleton and need joints to move
A Hard exoskeleton is bad for growth and movement, but good for living in terrestrial or dry environments
What are Myriapoda
Myriapoda are terrestrial with largely repreating segments, with a pair of antennae and jaw like mandibles
It includes Millipedes and Centipedes
The likely colonizers of land were probably like this
What are Chelicerata
Have mouthparts called Cheliceae and typically 4 pairs of legs
Scorpions, spiders, mites, horseshoe crabs
What are Trilobites
- common in Cambrian
- extinct 300 million years after that
- no living descendants
What are insects
- Insects are the largest class of organism
- they are diverse in form, always have 6 legs
- 1/2 of Eukaryotes
- dominant terrestrial life
- first flying animals, wings emerged from thorax
- Giant insects were common in the Carboniferous
- Some insects are essentially a modified appendage originating from a 3rd pair of wings found in “tree hopper”
What is Pancrustacea
traditionally Insects are treated separatly from Crustaceans, but data suggests they should be within it (called Pancrustacea).
What are the two types of Metamorphosis
Incomplete Metamorphosis
- young called nymphs go through a series of molts to reach adulthood
- most insects
Complete Metamorphosis
- larval stage like maggots, grules, and caterpillars
- Still molt
What are haplo-diploids
Haplo-diploids insects like wasps, bees, and ants have fertilized eggs which make females, multicellular diploids
and Unfertilized eggs which make males, multicellular haploids
How have insects affected plants
Insects have a lot of influence on plant evolution.
Mobile terrestrial animals, pollination and co-diversification of angiosperms
While insect herbivory also had an affect
What are Parasitoids
Parasitoid insects (like many wasps) use a host to feed their larva.
Eggs are layed on or in the host which the larvae feed on after hatching. The host is completely consumed
Hyperparasitoids are parasitoids of parasitoids
What percent of insects are beetles
40% of insects are beetles, which is 25% of animals
Where do insects live
Insects live pretty much everywhere and fill many ecological niches.
Insects colonize freshwater aquatic habitats
But No Marine Insects
What are the three main groups of Crustaceans
Decapods - lobsters, crabs, shrimp, and crayfish
Amphipods - Copepods, barnacles, cirripods
Cladocerans - ostracods, stomatopes, isopods
What are copepods
Copepods are the most abundant along with other planktonic crustaceans make up a massive part of animal biomass in oceans
what are isopods
Isopods = most diverse (10k species) on land
what are stomatops
Stomatopods = mantis shrimp, which have 16 colour receptors and punch good
what are Cirripods
Cirripods = barnacles
