Lab04_4

Lab Activity 4.4
Spiny Skinned Animals and Chordates

Study the instructional material below. Be sure to click on each of the photographs for an enlarged view in a separate window. The larger version is necessary to complete the assignment. It opens in a separate window which can be resized by grabbing the bottom right corner and dragging it. It can also be moved by grabbing the top heading bar and dragging it. Be sure to close the extra window by using the X in IBM, or the close box in MAC when you are finished using them.

Introduction

Marine invertebrates are animals without backbones that live in the sea. Over 97 percent of all animal species are invertebrates and the majority of these are marine. These species are divided into 33 phyla of which two related phyla the Echinoderms (spiny skinned animals) and the Chordates (notocord animals) will be featured in this lab activity.

Instruction

Examine the photographs of the invertebrates depicted below. Study the descriptions that go with each photograph and learn the stated information about the biology of each one.

Be sure to write about what you are learning in the lab section of your notebook. You will be expected to answer questions about the lab activity during the lab self test and lab quiz. It helps to have your text and coloring books open beside you for support.

Supporting Information

Refer to the Assigned Readings Below:
Marine Biology Textbook	Chapter 7, pages 142 to 147
Marine Biology Coloring Book	Plates 39 to 42

Phylum Echinodermata (spiny skin animals): Sea Stars, Brittle Stars, Feather Stars, Sea Urchins, Sand Dollars, and Sea Cucumbers
1. Sea stars, like many other echinoderms, have radial symmetry with arms arranged in a circle around a central disc.
2. The ambulacral grooves of the arms contain tube feet, which are tiny suckers used in locomotion.
3. Sea stars are usually carnivorous predators using their suckers to capture and manipulate prey.
4. The arms of a brittle star are flexible, narrow, and emerge abruptly from the central body disc.
5. A brittle star is able to violently contract the muscles in its arms severing portions when trapped. This defense mechanism, called autotomy, allows the star to escape the grasp of an enemy.
6. Brittle stars are the fastest echinoderms. They move their arms in a rowing motion that propels them along.
7. Crinoids have feather-like arms radiating from a stalk-like body called the calyx.
8. Feather stars lack the long stalks of their relatives the sea lilies.
9. Crinoids orient themselves with their oral side facing up.
10. The skeletal plates of an urchin are tightly joined to form a rigid skeleton called a test.
11. The body of an urchin is covered with spines.
12. Sand dollars are urchins whose bodies are flat and whose spines are small.
13. Sea cucumbers lack arms and have bodies that are stretched out along the oral-anal axis.
14. Sea cucumbers have thick, leathery bodies that are worm-like and flexible.
15. The long, tentacular, oral tube feet that surround the mouth of a sea cucumber are used to collect food.

Phylum Chordata (notocord animals): Tunicates, Sea Lancelets, and Vertebrates
1. Sea squirts are filter feeders that create a water current that passes through their pharynx. Food particles are filtered from the water current, entangled in a strand of mucous, and passed into the stomach.
2. Sea squirts are also called tunicates, a reference to their cellulose covering, called the tunic.
3. Although adult tunicates are attached to the bottom, they produce free-swimming tadpole larvae that look like little fish.
4. The bodies of cephalochordates, like Amphioxus, are fish-like and pointed at both ends.
5. The muscles of Amphioxus' body are arranged into V-shaped segments called myomeres that act upon a stiff but flexible rod called the notocord.
6. Sea lancelets, like sea squirts, are filter feeders that use their ciliated pharynx to capture food particles.

Lesson 4

Lab Activity 4.3 Molluscs and Jointed Legged Animals