Protosomes

The terms ‘Protostome” and “Deuterostome” are generally used to describe a particular developmental characteristic/pattern. Explain.

describe different patterns of embryonic development, particularly how the early embryo forms the mouth and anus and how cleavage and coelom formation occur.

Fill in: Many bilaterian phyla first appear in the fossil recording during the __________________________.

Cambrian explosion

What are the three bilaterian clades?

• lophotrochozoa

• ecdysozoa

* these clades are protosome clades

• deuterostomia

What are some adaptations that made the transition to land possible in some animals?

• the evolution of lungs

• the transformation of fins into limbs

• structural changes for weight-bearing (vertebrae)

• specialized eggs that retained water

What is a genetic toolkit and how does it relate to diversification of animal body plans?

provides a common set of developmental genes, and evolution modifies the regulation of these genes, leading to the wide diversity of animal body plans seen today.

What are the two major clades of protostomes? What are the key phyla in each?

Ecdysozoa

• key phyla

  • nematoda

  • arthropoda

Lophotrochozoa

• key phyla

  • platyhelminthes

  • mollusca

  • annelida

Which protostome phyla exhibit the synapomorphy segmentation?

Lophotrochozoa: Phylum Annelida

What is a lophophore?

ciliated feeding structure

What is a trochophore?

ciliated larval stage

understand the key characteristics of Platyhelminthes as presented.

• flattened body to allow gas exchange

  • high surface area to volume ratio

• incomplete gut

  • gastrovascular cavity

• acoelomates

What are the common names of members of platyhelminthes? Which are parasitic and which are free-living?

• flatworms:

  • free-living flatworms (turbellarians)

  • flukes (parasitic)

  • tapeworms (parasitic)

What are the common names of members of annelida? How do these groups differ in terms of habitat and lifestyle (parasitic? Free-living?)

Annelids include:

• earthworms, terrestrial and aquatic (free-living)

• marine annelids (free-living)

• leeches

  • mostly freshwater

  • many are ectoparasites (feed on blood, some are predators)

understand the key characteristics of annelida as presented.

• segmented worms; coelomates

• complete digestive tract (mouth and anus)

• setae on some (bristle-like extensions)

• synaporphy: segmentation

understand the key characteristics of Mollusca as presented.

• ceolomates

• specialized modular plan

• complete digestive tract

what are the 3 body regions of a mollusk? which secretes the shell?

• foot: large muscle at base of an animal

• visceral mass (houses internal organs): digestive, reproductive, excertory organs

• mantle: secretes shell

  • mantle cavity: encloses the respiratory structures

what are the 3 major classes of mollusks? what are common names of organisms found in each?

• class bivalvia

  • clams, mussels, scallops, oysters

• class gastropoda

  • snails, slugs

• class cephalopoda

  • squids, octopus

What characteristic (synapomorphy) unites all animals within the Ecdysozoa?

possession of a three-layered cuticle (exoskeleton)

Two minor ecdysozoan phyla: Tardigrada and Onychophora (velvet worms), are closely related to Arthropods. What are two morphological characteristics that tardigrades and velvet worms share with the arthropods?

segmented body and limbs

What is a nematode? What is an importance of free-living soil dwelling nematodes?

free-living unsegmented roundworms

• they are important in breakdown and recycling of organic matter

How do some nematodes impact human health?

parasitize humans: lives and multiples in human intestines

Why do nematodes swim in a typical “S” or whiplike fashion?

they have a hydrostatic skeleton

understand the key characteristics of nematoda as presented.

• roundworms

  • unsegmented

  • pseudocoelomates

• complete digestive tract

• hydrostatic skeleton

What are 2 advantages gained by the presence of an exoskeleton?

• allows for muscle attachment

• protection from predation and dessication

What are the 3 major subphyla of arthropods?

• myriapoda

• chelicerata

• pancrustacea

What are the classes found within each (subphyla of arthropods), and what types of organisms (common names) are found in each group?

• subphylum myriapoda

  • class chilopoda (centipedes)

  • class diplopoda (millipeded)

• subphylum chelicerata

  • class arachnida (spiders, ticks, mites, scorpions

• subphylum pancrustacea (lobsters, crabs, shrimp, barnacles, isopods, copepods

  • class insecta (ladybug)

Subphylum Myriapoda

• Class Chilopoda

• Class Diplopoda

• Class Chilopoda

  • carnivorous: hunt and eat insects

  • anterior appendages modified into venomous fangs/claws

  • one pair legs/segment (= two legs per segment)

• Class Diplopoda

  • detritivores: eat dead organic matter

  • two pairs legs/ segment (= four legs per segment)

Subphylum Chelicerta

• Class Arachnida

have two major tagmata

• cephalothorax and abdomen

fang-tipped chelicerae

some are predators (spiders and scorpions)

some are ectoparasites (mites and ticks)

Subphylum Pancrustacea

• crustaceans

• class insecta

Crustaceans

• mostly aquatic

• synapomorphy

  • 2 pairs of anntenaes

  • biramous (branched) appendages

  • two tagmata: cephalothorax and abdomen

• modified body forms

Class insects

• most can fly

• synapomorphy

  • three tagmata (head, thorax, abdomen)

  • modified appendages

    • 1 pair of antennae

    • 1 pair of mandibles

    • 3 pairs of walking legs

    • 1-2 pairs of wings

How do centipedes differ from millipedes? What are the class names for these organisms?

• Class Chilopoda (centipedes)

  • carnivorous: hunt and eat insects

  • anterior appendages modified into venomous fangs/claws

  • one pair legs/segment (= two legs per segment)

• Class Diplopoda (millipedes)

  • detritivores: eat dead organic matter

  • two pairs legs/ segment (= four legs per segment)

What habitats do crustaceans occupy? What structural characteristics distinguish crustaceans from other arthropods?

Crustaceans

• mostly aquatic

• synapomorphy

  • 2 pairs of anntenaes

  • biramous (branched) appendages

  • two tagmata: cephalothorax and abdomen

• modified body forms

What are the most prominent anatomical features of insects?

• 1 pair of antennae

• 1 pair of mandibles

• 3 pairs of walking legs

• 1-2 pairs of wings

What are the 2 major types of metamorphoses employed by insects, and how do they differ?

• incomplete metamorphosis

  • egg → nymph → adult

• complete metamorphosis

  • egg → larva → pupa → adult

Which protostomes are acoelomates?

Phylum Platyhelminthes (flatworms: turbellarians, flukes, and tapeworms)

Which protosomes are pseudocoelomates?

Phylum Nematoda (roundworms)

Which protosomes are coelomates?

Phylum Annelida (earthworms, marine annelids, leeches)

How would you explain the difference between a spider and an insect to someone who has not taken Biology 106? What are some differences between spiders and insects?

insects = 6 legs, 3 body parts, antennae (sometimes wings), while spiders = 8 legs, 2 body parts, no antennae, no wings.

Which phylum is the most successful phylum in terms of diversity?

phylum arthropoda

pick your favorite insect, tell me the order name, an insect belonging to that order, and one fact about that order

My favorite insect order is Lepidoptera.

• Order name: Lepidoptera

• Example insect: butterfly

• One fact: Lepidopterans have wings covered in tiny scales, which is actually what their name means (“lepido” = scale, “ptera” = wings). These scales give butterflies and moths their colors and patterns.