Bay Experience
Underwater Critters in your Backyard Bay
Objectives:
• Understand the concepts of diversity and adaptation
• Become familiar with both native and invasive species of Narragansett Bay
Background Information:
Narragansett Bay is home to many different marine creatures including fish, crabs, shellfish, and even
seals. We will focus on critter habitats, food webs, and adaptations.
Activity:
We will explore the concepts of diversity, adaptations, food webs and habitats through the use of live
animals. We will discuss each animal, showing how each part of the animal is important to its
survival. You will also learn how to differentiate between genders and discover how important
adaptations and diversity of species are to animals that live in Narragansett Bay and to the food web.
Animals that may be used (Based on availability):
Blue mussels (Mytilus edulis)- They moor themselves with tough Bissell
threads, usually in dense masses, and compete with barnacles to cover
intertidal rocks and pilings. In prime locations, full growth occurs in
approximately one year, but in other locations it can take up to three. Like
all bivalves, they are filter feeders. These are the kinds of mussels that are
eaten in restaurants. They are also eaten by sea stars.
Ribbed mussels (Geukensia demissaGeukensia demissaGeukensia demissa)Usually found in salt marshes, buried in the mucky peat among the roots of salt
marsh grasses. Very rugged; can handle high temperatures and salinity double
that of sea water. These are inedible.
Periwinkles (Littorina spp.)- The most abundant snails in New England.
These are abundant inter-tidally, and will attach to anything solid. They
can withstand long periods of being out of the water. They are herbivores,
and eat mostly algae attached to rocks. They are widely eaten in Europe;
steamed or quick boiled in salt water, then eaten with butter.
Oyster drills (Urosalpinx cinerea)- They are found in the intertidal to subtidal zone, down to about 50 feet (15 m). Although they like brackish
water, they will not willingly go to places with salinity less than 15 ppt.
These snails drill a small hole with their radula, and suck out the soft
parts of the shellfish as food. As the name would imply, oysters are their
favorite food. Shell-fishermen have, in certain areas, moved their oyster
farms closer to fresh water inputs to avoid these predators from eating
their stocks.
Channeled whelks (Busycon canaliculatum)- Channeled whelks like
to remain in water all the time, living in the subtidal zone down to
about 60 feet (18 m). Their egg capsules grow in long strings and
can often be found washed up on the beach. They often eat other
gastropods by using their hard shells to chip away at other
gastropod casings. They are the largest sea snails on the
Northwest Atlantic coast, and are eaten in the Italian dish Scungili
despite their rubbery texture. They are also called “conch” shells.
Hermit Crabs (Pagurus spp.)- Smaller species are found residing in
periwinkle or oyster drill shells. Larger species are found in moon snail
or whelk shells. Hermit crabs only come out of their shells when they
find a suitable replacement as they outgrow their shell, or if they are
extremely stressed. Hermit crabs should never be pulled out of their
shells as they will quickly become prey.
Spider crabs (Libinia emarginata)- These are also called decorator
crabs or gardener crabs, because they plant algae all over their
bodies. They have extremely long legs for their body size, and are
pretty docile despite their scary looks. You can tell if a crab is male or
female by flipping it over so the carapace is facing the ground, and
seeing whether the bottom of the crab is a big circular shape (female,
good for holding eggs) or a narrower lighthouse shape (male).
Lobsters (Homarus americanus)- Lobsters have two claws; a pincher
claw and a crushers claw. They are scavengers but will also eat
shellfish and crabs using their claws. Males are rigid, and females are
softer and feathery. They can regenerate claws, legs, and antennae. They can swim using the large
muscle in their tail, which propels them in a backward motion, and is also the part of the lobster most
people like to eat the most. People also eat their claws and their livers, called tomalley.
Sea stars (Asterias spp.)- All are predators. They eat bivalves,
especially oysters, by grabbing onto them with their tube feet, or
podia, prying them open, and everting their stomachs into the
bivalve where it is digested. In turn, bottom feeding fishes eat
them. They can regenerate their legs, and have 5 eyes, one at
the tip of each leg, which see mainly just shadows. The orange
dot in the center of the disc is the madroporite. This is where the
sea star lets water in and out, which it uses to receive oxygen and
structure in its body. They can tolerate brackish water to salinities
of 15-20 ppt.
Purple Sea Urchins (Arbacia punctulata)- They are protected from
predators by the many spines that cover their bodies, which is also how
they move. They are omnivores, eating seaweed as well as sedentary
invertebrates and scavenging upon dead organisms. Their mouth is on
their underside, and the internal area where it sits is called “Aristotle’s
lantern”.
Rocky Shore
Life’s Tough at the Rocky Shore
What adaptations do plants and animals that exist on the rocky shore have to
help them live in such a harsh environment?
Objectives:
• Use scientific equipment and a data sheet to collect information.
• Explain how an organism’s adaptations help it to survive on the rocky shore.
• Understand how environmental factors affect where an organism lives.
Background Information:
A Rocky Shore is an area where the wave action is so strong that sand and mud can not settle;
leaving a coastline of exposed rock. As one might expect, a rock pounded by crashing waves is a
difficult place to live for many animals and plants. Organisms must be able to withstand changes in
tides, pounding waves, extremes of temperature and salinity and aerial assault by gulls. Temperature
extremes are mainly due to shallow waters, which are much easier to warm by the sun or cool by the
wind. Salinity extremes are primarily due to evaporation of water in tide pools, which causes some
tide pools to reach salinities much higher than ocean water.
As a result to these extreme conditions only organisms specifically adapted to the rocky shore are
able to live there. Adaptations are features of an organism’s body that allow it to live comfortably in
its habitat. For example, the shells of mussels, periwinkles, dog whelks, oyster drills, hermit crabs
and the exoskeletons of green and Asian shore crabs protect those animals from the crashing waves.
Rock-weed, kelp, and Irish moss are seaweeds that have holdfasts to anchor them to the rocks.
These holdfasts are not roots, but instead serve to anchor the plant in place in the face of the power
of waves and tides. Sea stars use their tube feet for the same purpose, to keep them attached to
rocks. Green and Asian shore crabs use their coloring to camouflage themselves into the rocks and
seaweed in which they hide. Mussels, barnacles, periwinkles, and slipper shells all open or come out
of their shells to eat when the tide is in, but are able to close their bodies completely inside their shell
to conserve water when the tide is out. These are just a few of the many adaptations of the most
common rocky shore animals.
Rocky shores have four distinct zones. Different organisms are able to live in each of these
areas.
1. The sub-tidal zone is the area that is always covered by water, even at low tide.
2. The inter-tidal zone is the area that is covered by water part of the day.
3. The high tide zone is the area that is only covered during high tide.
4. The splash zone is the area that is sometimes splashed by sea-water, but never
submerged.
Activity:
You will collect plants and animals ~ at least 10 things that are alive or once were alive. After the
collection period you will use field guides to identify your organisms. Each group will present one
organism to the whole group.
Questions to Consider:
• What are the differences between upper inter-tidal and lower inter-tidal pools? Why did you find
these differences?
• What generalizations can you make about tide pools closer to the water versus tide pools further
away?
• What plants and animals are common on the rocky shore? Where do they generally live?
• What adaptations do these plants and animals have to help them live in such a
harsh environment?
Biodiversity trawl
“What organisms can be found at the bottom of the bay?”
Activity:
You will research this question by studying field guides and then create a hypothesis about the
abundance and diversity these organisms.
To test your hypothesis, you will conduct a trawl aboard the Save the Bay vessel Alletta Morris.
After, you will analyze the data collected.
Objectives: At the end of this program learners will be able to:
• Use field guides to identify organisms
• Collect data and analyze data
• Calculate the percentages for each organism collected on during the trawl.
BEFORE THE TRAWL…
QUESTION: “What organisms can be found at the bottom of the bay?”
YOUR HYPOTHESIS:
WHILE COLLECTING PLANTS AND ANIMALS…
RECORD DATA:
Type of Number/ Description or drawing of organism
organism Size found
Other notes
Type of Number/ Description or drawing of organism
organism Size found
Other notes
AFTER COLLECTING PLANTS AND ANIMALS…
ANALYZE DATA:
Which types of organisms did you mostly find today?
DRAW A CONCLUSION:
What does the presence of these animals tell us about the health of the Bay?
Additional Observations:
Name ___________________________
Using All My Senses
Fill in the graphic organizer with the senses or emotions from our Bay Experience.
Things you can
see
Things you can
smell
Things you can
touch or feel
Things you can
hear
Emotions from
our experience