HW 12: CH33 Invertebrates

For each of the three major clades of bilaterians, what (if anything) can be inferred about whether the common ancestor of the clade had a coelom?

The common ancestor of the Deuterostomia had a coelom, but we cannot infer anything about the ancestor of the Lophotrochozoa or the Ecdysozoa.

Soft-shell crab is a prized dish in many ocean-side resorts. Which of the following statements provides the best explanation for the soft shell of the crabs?

The crab has just molted and the new exoskeleton has not yet hardened.

In the figure above, assume that the two medusae shown at step 4 were produced by one polyp colony. Use your understanding of mitosis and meiosis to select which of the following is true.

The medusae are genetically identical but the gametes differ genetically.

To what extent has the presence of a coelom in animals changed over the course of evolution?

The presence or absence of a coelom appears to have changed multiple times during the course of evolution.

Which phylum is characterized by animals that have a segmented body?

arhthropoda

Which two main clades branch from the most recent common ancestor of the eumetazoans?

cnidaria and bilateria

Our understanding of many of the evolutionary relationships among animals changed after those phylogenies were based on morphological and molecular data (as opposed to only using morphological data). Which of the following groups represents an example of this change?

lophotrochozoa

Our understanding of many of the evolutionary relationships among animals changed after those phylogenies were based on morphological and molecular data (as opposed to only using morphological data).What do these changes indicate?

molecular studies add additional information to morphological studies and improve our understanding of evolutionary history

While sampling marine plankton in a lab, a student encounters large numbers of fertilized eggs. The student rears some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth. The embryo develops into a trochophore larva and eventually has a coelom and a hemocoel. To which group of organisms did these eggs likely belong?

molluscs

You work for the Iowa Department of Natural Resources and are inventorying mussels in the Cedar River. You find similar results to those in this research. Which of the following is true?

mussel populations are declining

The heartworms that can accumulate within the hearts of dogs and other mammals have a hemocoel, an alimentary canal, and an outer covering that is occasionally shed. To which phylum does the heartworm belong?

nematoda

Which of the following statements best explains how planarians can survive and thrive without respiratory or circulatory systems?

none of their cells are far removed from the gastrovascular cavity or from the external environment

Your friend is studying a mass die-off of warblers in Canada. Which of the following is most likely to lead your friend to believe a pathogen is the cause?

only warblers are affected

Do the results support hypothesis (1), hypothesis (2), or both?

- moth capture by species A supports hypothesis 2 - moth capture by species B supports hypothesis 1

Why did the researchers use naive bats in this study?

- to estimate the ability of bats to learn - to avoid a situation when experienced bats know how to capture moths

Which of the following combinations of phylum and description is correct?

Platyhelminthes−−flatworms, gastrovascular cavity, no body cavity

Nematodes and arthropods are the largest ecdysozoan phyla. Which of the following statements are true?

- arthropods possess an open circulatory system - arthropods are named for their jointed appendages - both nematodes and arthropods must mold in order to increase in size - both nematodes and arthropods possess an external covering, or cuticle - some nematodes are parasitic on humans

Select the correct statement(s) about invertebrate taxa.

- ectoprocts lack a distinct head - tapeworms lack a mouth and gastrovascular cavity - rotifers are smaller than many protists

The phylum Arthropoda includes four major lineages: cheliceriforms (also called chelicerates); myriapods; insects and their relatives (together called hexapods); and crustaceans.

CHELICERIFORMS: arachnids, horseshoe crab, possess clawlike feeding appendages MYRIAPODS: exclusively terrestrial, millipedes and centipedes INSECTS: wings allow flight, butterfly, body divided into heat thorax and abdomen, three pairs of walking legs CRUSTACEANS: primarily aquatic, crabs and isopods, two pairs of antennae

Which of the following statements is correct with respect to the evolutionary relationship between chordates and invertebrates?

Chordates are more closely related to echinoderms than to arthropods.

Complete a phylogenetic tree of Bilateria that includes the ten phyla of bilaterians. Label each branch that leads to a phylum with a C, H, HC, or N, depending on whether members of the phylum have a coelom only (C), hemocoel only (H), hemocoel and reduced coelom (HC), or no body cavity (N).

Hemichordata - C Echinodermata - C Chordata - C Platyhelminthes - N Syndermata - H Ectoprocta - C Brachiopoda - C Mollusca - HC Annelida - C Nematoda - H Arthropoda - HC

Complete an overview of the evolutionary history of invertebrate life. Match the terms in the left column to the appropriate blanks in the sentences on the right. Not all terms will be used.

In terms of evolutionary history, the first animals were INVERTEBRATES. Early in animal evolution, some groups such as SPONGES and (later) CNIDARIANS diverged from all other animal groups. Most invertebrates are BILATERIANS, an enormous clade that has diverged into the three major clades: LOPHOTROCHOZOA, Ecdysozoa, and Deuterostomia.

Collectively, do these beetles and all other invertebrate species combined form a monophyletic group? Why?

No. Invertebrate species in phylum Chordata are more closely related to vertebrates than they are to other invertebrates.

A land snail, a clam, and an octopus all share

a mantle

Insects are the most diverse group of organisms, in terms of numbers of species, dominating terrestrial habitats. More than 30 orders of insects have been described, with the order Coleoptera being the largest. Classification is based on traits such as wings and mouthparts. All insects have a three-part body plan consisting of a head, thorax, and abdomen; three pairs of walking legs; and one or two pairs of wings. The chart below indicates defining characteristics for eight of the more than 30 orders of insects.

a) hard forewings protect membranouus hindwings b) hindwings reduced to stabilizers c) wings have scales d) hairy wings e) complete metamorphosis f) incomplete metamorphosis g) flies h) "true bugs" i) butterflies, moths j) caddisflies

In order to restore mussel populations in U.S. rivers, which of the following would likely be best?

restore rivers to their former natural state

Your environmental science class visits a local stream to look for mussels. Where are you most likely to find some?

sitting on the bottom of the stream

Which of the following statements describes how healthy corals appear brightly colored?

they host symbionts with colorful photosynthetic pigments

Why do large animals need specialized organs for gas exchange?

volume increases more rapidly than surface area as size increases

If trends in mussel populations continue, which of the following is most impacted in fresh waters?

water filtration