From previous labs:
Sponges:
Check your sponge cultures. Did any of your cells attach and start to form the clumps of cells that will eventually turn into baby sponges? If so take a photograph or two to compare to the photograph of dissociated cells from last week.
No results? I noticed sponges sent were particularly loaded with hard debris, which interfered with cell isolation. We made super concentrated suspensions of cells for the class Thursday night. Every table should look at one of the five super cultures. All are showing some cell aggregation except for the purple sponge. I took pictures every second day and your lab instructor can show you the folder containing these shots. You can substitute or add the information for a class culture to your own data.
Sea spiders: I had to wait for a large order from MBL to order enough to be able to ask for sea spiders. You have seen pictures, now observe the real animal. Describe the overall anatomy of the spider. Estimate the length of the body to that of the long legs. Note that the "body" is not that much thicker than the legs, although terming the central cylinder a body is somewhat misleading as part of the GI tract + extend into the legs.
Dorsal surface showing proboscis, eyes and chelifores (appendages used to tear bits of food).
Ventral surface showing oviger (used by males to carry eggs0 and gonopores or opening to reproductive organs.
Part 2:Cnidaria and Ctenophora: External anatomy and survey of living forms.
Ctenophores:
Background information:
Ctenophorans range in size from only half a centimeter in length to over 1 meter long. Ctenophorans either drift with the current or are weak swimmers using ctene (comb plates) consisting of hundreds of partially fused cilia arranged along eight longitudinal comb rows. Comb jellies are predators, and their tentacles are armed with unique, sticky colloblast cells that capture small invertebrate prey. Once trapped, either muscle in the core of the tentacle contracts to pull food toward the mouth. Ctenophorans are often found in perpetually dark parts of the oceans, and like other animals that inhabit this environment, the use of light bioluminescence has become an important tool for attracting prey, signaling danger, or finding a mate.
1. Obtain a dish containing a comb jelly . Fed it a few brine shrimp larvae or other food available. They may not feed. Do not use much light or you will overheat and kill these animals. You can watch the shrimp move down the gut. Then turn off all lights of the microscope, light from the bottom but dimly against a dark plate, or from above but only with very dim light. The cilia will refract light and you should be entertained by the light show of blue, yellow and red refractive waves of light moving down the cilia. These are delicate animals and we do not want to stress them, so a table should make its observations using one stereoscope. If we obtain enough specimens, each table should try for a quick movie of their specimen either feeding or just record the light show caused by their movement. Check periodically with your lab instructor so she can add fresh seawater after feedings. Record your observations in your journal.
______
Cnidaria: Colonies of various hydrozoans.
2. Your second exercise will be to continue to look at variation among the class Hydrozoa. In all specimens examined, you should determine (if only from the web) what life stages to expect and whether the colonies exhibit polymorphisms.
a. In all cases, record the other invertebrates present and living on the colony. Film at least one of the different animals that are feeding or living on the Tubularia colonies.
b. Take photographs of the different types of polyps present. In your journal compare and contrast the different types of polyps found.
c. Film feeding in one of the colonies available.
d. Identify all life stages that can be observed and determine from web search or the background information provided the number of different life stages exhibited by each species examined.
Specimens that may be available
Clava spp. (Not sent)
The word Clava, the genus of the club hydroid, means "club". It gets this name because of the bunches of reproductive organs under the hydranth which give it a club-like appearance The polyps have 30 to 40 tentacles and have reproductive bodies clustered on short branches below the tentacles. The polyps are pink, white or red. In most species larvae develop from fertilized eggs and once settled give rise to new colonies.
Tubularia sp.Several colonies are available all in different phases of the life cycle. If you obtain a colony that consists mainly of feeding polyps, make sure you view gonophores which essentially function when mature as attached medusa on another group's prep.
These are exceptional beautiful hydroids. There are many unbranched stems in a colony, each one ending in a feeding polyp (hydranth) with two groups of tentacles: short oral tentacles around the mouth and long aboral tentacles arranged about the base of the polyp. Reproductive structures (gonophores) hang between the two sets of tentacles with developing eggs and larvae clearly visible. The number of gonophores varies with species and sometimes colony size. The color of the stems and tentacles is usually a pale-green to white but the rest of polyp may be hues of orange, pink or even bright red.
Life cycle
Hydractinia echinata
Obtain a hermit crab or at least a shell containing a colony of Hydractinia echinata. Identify if you can at least four types of individuals. Draw the different individuals you see. Graph the colony indicating the position of the various individuals to each other. Do not attempt in this drawing to show each individual but do indicate relative numbers and overall pattern. Watch carefully for epifauna. Various tubed annelids often live among the hydroids. Although considered a plus for the annelids that are protected, this relationship may be a minus for the hydroid colony as I have seen the worms steal food from the hydroids. Also look for other hydroids that may be competing with Hydractinia echina for space. Colonies that have to share their shell with these competitors may have different numbers of different individual or place their individuals in different positions relative to the intruding species. If you had to design a colony where would you place reproductives relative to defense individuals? Would the placements vary dependent on whether competitors were present or absent?
Colonies are often male or female (or more strictly speaking have only male or female gonozoids). Can you tell whether the colony on your shell is a male or female colony? Construct hypotheses regarding different conditions and then see if the distribution supports your hypotheses. Each pair should collect data on one shell.
Another diagram that divides the colony into non reproductive zooids and female and male reproductive zooids.
Shells for your to use to plot distribution of different zooids. Choose the shell shapes that best fit the shell of your crab. Jpegs are available on schedule for you to use in photoshop
Shape one
Are there any polyps on the underside of the shell? Use the diagram below.
Shape two, front, side views and ventral (bottom) of shell
Shape three: