Common seashore animals of Southeastern Alaska - Juneau Nature

170 Pages·2013·14.42 MB·English

Common seashore animals
of Southeastern Alaska
A field guide by
Aaron Baldwin
All pictures taken by Aaron Baldwin Last update 9/28/2013
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unless otherwise noted. [email protected]
Halichondria panicea – Crumb-of bread sponge Ophlitaspongia pennata– Red encrusting sponge
Color yellow, tan, green or light brown-purple. Mid to upper intertidal. The Forms bright red, thin crusts at the lowest intertidal zone. Several other
most common intertidal sponge in SE Alaska. similar species are sometimes found.
Sponges – Phylum Porifera
The vast majority of Alaska’s sponges live below the lowest
tide line. I have included here a few species encountered in
the intertidal zone as well as some deeper water species.With
a few exceptions, most sponges require microscopic
examination to identify.
There are three large groups of sponges. The Calcarea are
sponges with spicules composed of calcium carbonate only.
The Demospongia have calcium carbonate and silica
spicules. The Hexactinellida have only silica spicules. The
latter group are abundant deep water sponges and can be
several meters tall.
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Haliclona sp.– Purple intertidal sponge
Local species is undetermined and may be unnamed. May be purple,
green, yellow, or orange. Mid to high intertidal.
Spicules!
The “skeleton” of sponges is a complex matrix of proteins and
tiny structures called spicules. These spicules are commonly
made of calcium carbonate or silica (glass). These spicules
come in hundreds of shapes and sizes, and most sponges have
several different types. The form and combination of these is
unique to each sponge species and is how scientists identify
sponges.
Most shallow water sponges belong to the class Demospongia
and have spicules made of silica (glass) and a protein known as
spongin. Members of the class Hexactinellida are common
deepwater species in Alaska and have spicules made of silica
but never have spongin fibers. The smallest class is the
Calcarea which are distinguished by spicules made of calcite
Mycale adharens – Smooth scallop sponge o n l y a n d lacking spongin fibers.
Nearly always on the shells of scallops (Chlamys spp.). Usually forming a
thinner crust than does Myxilla incrustans (below).
Myxilla incrustans – Rough scallop sponge Illustration “Various forms of sponge spicules” from 3
As the name indicates, this sponge has a rough surface with many raised Augusta Foote Arnold’s “Sea Beach at Ebb Tide” 1903
oscula. May form massive clumps on scallops (Chlamys spp).
Photo by RN Clark
Neoesperiopsis digitata – Finger sponge Suberites domuncula latus– Hermit crab sponge
This subtidal sponge can be occasionally found in the drift zone, This subtidal sponge grows on shells occupied by hermit crabs and
especially following storms. Other species may be found. eventually dissolves the shell completely and grows with the hermit.
Heterochone calyx – Vase sponge 4
Cliona californiana – Boring sponge
A deep water species, these are occasionally snagged by fishing gear. A
Bright yellow spots on seashells and barnacles when alive. Remains of
very large sponge, often exceeding 1 meter in height!
seashells riddled with holes frequently seen in beach drift.
Aurelia labiata – Moon Jelly Cyanea capillata – Lions mane jellyfish
Easily distinguished by the four horseshoe-shaped gonads visible in The red or orange color on this species is distinct. These can give a
center of bell. Sometimes phosphorescent. painful sting. Sometimes strand on beach in large numbers.

Jellyfish, hydroids, corals, and sea
anemones – Phylum Cnidaria
This diverse phylum are united by the presence of
specialized stinging cells called nematocysts. These
are used both for defense and to immobilize prey.
There are four large groups of cnidarians found in
SE Alaska. These are; Scyphozoa (jellyfish),
Hydroida (hydroids and hydrocorals), Staurozoa
(stalked jellyfish), and Anthozoa (sea anemones and
corals).
Chrysaora melanaster– Sea nettle or Rising sun jelly 5
This oceanic species occasionally washes ashore following storms on the
outer coast. The radiating brown stripes are distinctive.
Aequorea victoria – Water jelly Polyorchis pencillatus – Red-eye jellyfish
Frequently seen around docks, the water or many-ribbed jelly has 80 or A small but often abundant jelly, this species is usually 1-3 cm in diameter.
more radial canals most visible around the margin. Bioluminescent. The ~100 or so small red eyes are distinct
Alternate life cycles!
All of the jellies on this page are the planktonic or medusa
stages of hydroids. When looking at the sessile or hydroid
phase (see the next page) one might never guess that these
medusae come from similar organisms. In fact, many times
the hydroid phase has been given a different scientific name
than the medusa until someone discovers that they are the
same animal! There are many medusae and hydroids that
have yet to be matched.
Typically the medusa stage is the sexual phase that will
produce larva (called planula). The larva will settle on the
seafloor and grow into the plant-like hydroid phase that
reproduces asexually and will eventually produce hundreds of
free swimming medusae.
Gonionemus vertens – Clinging jellyfish 6
Unlike many jellies this species often adheres to algae, eelgrass or other
fixed objects. One of several dozen hydromedusae found in SE Alaska.
Obelia spp. – Wine-glass hydroids Abietenaria spp. – Course sea firs
Brown, densely tufted algae-like growths. Abundant on floating docks. Usually in the lowest intertidal and subtidal. These have a fern-like growth
Complex species, difficult to identify. pattern and branches with tiny spines giving the ‘course’ appearance.
Hydroids – Plants or animals?
Hydroids are found nearly everywhere in Alaska’s marine
environment but are often overlooked or mistaken for
seaweeds. While exposed by the tides hydroids often do
resemble marine plants more than they do animals. But when
covered by water the careful observer will see hundreds of
tiny polyps emerge that resemble tiny sea anemones.
Often the polyps of hydroids come in two basic types. The
feeding polyps (gasterozoids) capture tiny animals from the
water and feed the colony. These are the most common polyp
type. The second type are called gonozoids and their job is to
produce the free-swimming medusae as seen on the previous
page.
Hydractinia spp.– Hermit crab fuzz
These fascinating hydroids nearly always grow on the snail shells 7
occupied by hermit crabs. The hydroid colony eventually becomes the
shell and will protect the hermit with their stinging cells.
Stylantheca petrographa – Encrusting hydrocorals Stylaster spp. – Branching hydrocorals
Superficially similar to coralline algae – look for abundant star-shaped Restricted to moderately deep water, these hydrocorals are sometimes
pores. Usually restricted to the lowest tide zones and subtidal. snagged by fishing gear.

Hard corals
Many people are surprised to learn that Alaska has a huge
diversity of corals. Most of these live in very deep water and
are rarely seen. These deepwater corals are the subject of
much study as they are important habitat for many fish,
crabs, and shrimp.
The two species above are actually hydroids with a hard
skeleton and are thus called “hydrocorals”. The cup corals
(left) as well as the sea pens and soft corals on the next page
are anthozoans. Anthozoan corals are related to the better-
known tropical reef corals, although species in Alaska do not
form true reefs.
Balanophyllia elegans – Orange cup coral 8
The only true stony coral likely to be encountered in the intertidal zone.
Found in semi-protected areas on the outer coast.
Ptilosarcus gurneyi – Orange sea pen Halipteris willemoesi – Giant sea pen
Rarely intertidal, common shallow subtidal species. Capable of retracting This sea pen is always subtidal but is sometimes caught by fishing gear.
completely into sand. Bioluminescent when disturbed. This species commonly exceeds 1 meter in height!

Sea pens and soft corals
The sea pens and soft corals (also called gorgonians) are
collectively known as “octocorals” because the structure of
the individual polyps tends to be in eights or multiples of
eight. The polyp below has its tentacles retracted but you can
count the body divisions
M ost of Alaska’s octocorals are very
deep water, but a few species are
shallow or are brought up by fishing
gear. In the Aleutian Islands and Gulf
of Alaska some deep water areas
have been designated “coral gardens”
and are protected from human
activities.
Gersemnia rubiformis – Sea raspberry 9
Uncommon intertidally except on outer coast, abundant subtidal species.
Coral lacking hard parts, polyps (right) extend from fleshy mass.
Primnoa pacifica – Red tree coral Isidella sp. – Bamboo coral
Probably the most commonly seen of the deep sea corals. Commonly The skeletons of bamboo corals are usually white with dark brown nodes.
snagged by longline or pot gear. Smells like cucumber when fresh! Polyps quickly become gelatinous when out of the water.
Deep Sea Corals
The species on this page are all representatives of a diverse
group known as deep sea corals. While most are found below
100 meters or more, a few species are shallower. These
corals, along with the hydrocorals (page 8) and deep-water
sponges are an important component of the deep oceans.
They create a complex, three dimensional bottom structure
that is used by a large number of other organisms for
protection.
These often large corals are usually seen when tangled in
fishing gear. Unfortunately, once they dislodged for the
bottom the colony cannot re-attach and will probably die.
Interest in preserving this fragile and important creatures has
resulted in the creation of areas where fishing activity is
Paragorgia arborea – Bubblegum coral 10
prohibited or limited.
This large, fragile coral is only occasionally seen when snagged by fishing
gear. Thick, fleshy yellow to pink or red branches distinctive.