Sea Squirt, Tunicate (Sea Pork) and Parchment Tubeworm

November 30, 2007

It was a wonderful day on the beach. Still in the low 70s, the low tide revealed a lot, but, no great shells. In their place were a lot of tunicates and parchment tube worms.
The Tunicates have a common name of Sea Pork. Some types are called sea squirts because they will squirt water when picked up and squeezed. The picture of the brown sack like animal is a Sea squirt (I squeezed this one as I took the picture so you could see the water coming out of it).
“Sea squirts are immobile marine invertebrates which extract food (plankton and organic material) from seawater pumped through a brachial sac in their body cavity. They are called sea squirts because they squirt' seawater. The scientific name for this class of animals is Ascidiacea, so scientists often refer to them as 'ascidians'. They are part of a wider grouping (sub-phylum) of marine invertebrates called 'tunicates'. This sea squirt has been tentatively identified as a Styela plicata.
This invasive sea squirt is known by the name Pleated Sea Squirt. Its scientific name is Styela plicata (Lesueur, 1823).It is also known as the rough tunicate.

The pleated tunicate, Styela plicata is a solitary benthic (an aggregate of organisms that live in the bio-geographic region that includes the bottom of a lake, sea, or ocean and the littoral and supralittoral zones of the shore)(that’s got to be a super word to mean so much while saying it so succinctly !) tunicate believed non-native to the east coast and the western Atlantic, but occurring there in some abundance. The oval, upright body is covered with a tough and leathery cellulose-containing tunic, with numerous rounded warts and pleated grooves and a pair of short siphons.
Individuals range in color from light tannish white to gray. Thin red or purple stripes on the insides of the four-lobed siphons are evident as cross-shaped markings at the tips of the closed siphons. Individuals can be found singly or in groups (Carlton and Ruckelshaus 1997, Kaplan 1999, NIMPIS 2002, USGS, ISSG)

Styela plicata is a hermaphrodite, with individuals starting out as functional males and then becoming functional females later in life. Sequential hermaphroditism insures fertilization through outcrossing. Sperm and eggs are shed to the water column via excurrent siphons and fertilization is external. (Yamaguchi 1975, NIMPIS 2002).

Styela plicata is a sessile (permanently attached), benthic filter-feeder. The incurrent siphon takes water into a sieve-like pharyngeal basket that filters out food of the appropriate size class before water is pumped from the animal via the excurrent siphon. Styela plicata is among the most common introduced ascidian species worldwide. Despite considerable evidence supporting the contention that the organism is not native to U.S. waters, Styela plicata was originally described in 1823 from specimens collected from the hull-fouling community on a ship in Philadelphia PA. The organism was reported from U.S. coastal waters ranging from North Carolina to Texas in the 1880s, and had been reported from California by 1915. It is thought to be native to the Indo-Pacific region. (Carlton and Ruckelshaus 1997, Lambert and Lambert 1998, Lambert 2001).

Styela plicata is a widespread and common fouler of buoys, pilings, nets and other floating or submerged manmade structures. It is also a common fouler of aquaculture cages, bags, and nets. If fouling is severe costly cleaning of culture gear is required to avoid still costlier loss of stocks (Da Rocha and Kramer 2005).

http://www.sms.si.edu/irlspec/Styela_plicata.htm

Kingdom Animalia
Phylum Chordata
Subphylum Tunicata Lamarck, 1816 -- ascidies, sea squirts, tunicates,
Class Ascidiacea
Order Enterogona
Suborder Aplousobranchia Lahille, 1887
Family Polyclinidae Milne-Edwards, 1841
Genus Aplidium Savigny, 1816
Species Aplidium glabrum (Verrill, 1871)

Aplidium glabrum This is the name of the purple tunicate pictured to the right. It is a colonial (colony) species that has zooids in a clear tunic. I had sent a note with photos to Gretchen Lambert who helps publish the Ascidian News out of Seattle WA and she is the one who tentatively identified this animal for me. It seems that it is very difficult to definitively identify the tunicate without dissecting the zooids from the animal and viewing them under a microscope. I'm such a novice, that I have no idea what each zooid looks like. I will continue to research and try to find out. ( I guess my first item of business is to buy a microscope - one that I can take pictures with!)
It is interesting that when I was researching information about this tunicate that scientists have been trying to determine the cytotoxicity to certain types of cancer tumor cells. The research is very promising for the pharmaceutical industry.




"The Chaetopterus parchment tubeworm feeds by fanning water through its home tube with its wing-like legs (fan parapodia). A bag of slime is excreted from two feeding legs (aliform notopodia). Water flows into this bag and out through its side, trapping tiny algal and mud particles. At its bottom end, the bag is continuously rolled up into a ball by the food cup. Once the ball is big enough, the bag is rolled up entirely and the compact ball of mucus transported to the mouth over a conveyor belt of whipping hairs (ciliated dorsal groove). " Dr. Floor Anthoni www.seafriends.org.nz/indepth/invasion.htm

Atlantic Calico Scallop and Florida Fighting Conch

The Calico Scallop Argopecten gibbus (Linnaeus)
Is a bivalve ranging in size from 1-3 inches. It is almost circular in shape and has equally sized ears. The exterior of the right valve is white-yellowish and usually splotched or striped with colors of red or purple. The left valve is darker in color usually with red, orange or purple variegated with white or yellow- white. This scallop is commercially fished especially off both North Carolina and eastern Florida coasts. It is found only in the ocean and lives in 100 foot depths from Delaware to Brazil.
The live scallop has rows of eyes each having its own lens and retina, but it has no center of vision in its brain and probably can't form an image. It can however distinguish light and dark. It moves by opening and closing its shell. The dark variegated scallops are also calico but a chemical reaction occurred in these shells in which the calcium carbonate had been replaced with iron sulfide when the scallops were buried in the offshore muck and lacked oxygen.(Florida's Fabulous Seashells - Williams/Carmichael)

Florida Fighting Conch Strombus alatus (Gmelin)
is 2-4.5 inches and is a thick shell and is yellow-brown to reddish brown in color often with pale spots or stripes. It's axial ribs are crossed by spiral cords and gradually become larger and more separated and knobbed. It has a stromboid notch on its lower end of the canal. This notch is typical of all true conches - hence, they are in the family of Strombidae.
A herbivore, it feeds on red algae and is found offshore from North Carolina to Texas and Mexico. Like the Atlantic Calico Scallop above, it is also commercially fished chiefly for steaks, chowders and salads.

Common Paper Nauttilus, Cross-Barred Venus

The Common Paper Nautilus or Common Paper Argonaut is not really a shell in the true sense of the word. It is actually an egg case secreted by two arms of the female Argonauta argo (Linnaeus). Most shells will be secreted by the mantle of the mollusk, but not this one. I found this in the sargasso grass on Del Rey Beach, Florida on a recent trip there.
The animal is in the class Cephalopoda which is composed of the squid, octopus and nautilus. Most are predatory carnivores.
Only the female secretes the shell, the male Argonaut is much smaller and does not have a shell. They are usually found in tropic or temperate seas. The female can grow to the length of 2 feet and produce a shell as big as 14 inches long, these are nowhere near that size. They swim near the surface of the water and prey upon pteropod mollusks and small pelagic fish. Sailfish in turn, prey upon them.

Cross-Barred Venus, Chione cancellata (Linne) are one of the most plentiful shells on the island. They seem to come in a variety of colors depending on the sediment in their environment. They are heavy with strong, raised concentric ridges and rounded ribs that form a network of raised lines. Found in shallow waters, they are the main food source of the green and blue crab as well as moon snails. When you come across some with 'ready made holes for stringing', those have been likely drilled by the moon snail.

Seashore Creatures - Cannonball Jellyfish and Portuguese Man-of-War

Cannonball Jellyfish (Stomolophus Meleagris) Class Scyphozoa
I hadn't gotten around to putting these on the blog, but I definately enjoyed finding them. On the 8th of June, there were quite a few jelly fish and a few Portuguese man-of-war on the beach, along with a lot of sargassum weed.

The Cannonball Jellyfish is 5-7 inches high and 7-9 inches wide. It floats near shore and is found from the Chesapeake Bay to Texas, the Bahamas and the West Indies. The books don't have a caution about this animal.



The Portuguese Man-of-War (Physalia physalis) is another story.

It's class is Hydrozoa and It can be found up to 12 inches long and 6 inches high by 5 inches wide. It floats by being gas filled and is iridescent blue and pink with tentacles of different lengths, some being more than 60 feet long and containing stinging cells.

The books warn that it is highly toxic and "the tentacles contain one of the most powerful poisons known in marine animals and can inflict severe burns and blisters even when the animal is dead on the beach." (National Audubon Society Field Guide To Seashore Creatures)

I'm still just learning about everything on the beach, but, I sure knew enough to stay away from this!

Crenulated Pyram, Atlantic Oyster Drill, New England Basket Shell

Crenulated Pyram Pyramidella crenulata (Holmes) is a small (1/2 inch) shell with smooth, flat-sided whorls and deeply incised sutures. It's cream with tan blotches and lives in mud and in grass from the low-tide line to 50' sandy ocean bottoms. It can be found from North Carolina to Texas. It is a parasite that feeds on the soft tissues of other mollusks and marine animals.







The Atlantic Oyster Drill Urosalpinx cinerea (Say) Is a small shell measuring from 1/2 inch to 1 1/2 inch high. It's oval with an elevated spire and is grayish or yellow-white with a rough exterior with large axial ribs forming a pattern of raised wavy lines. It lives in sounds and inlets. Commonly found living in oyster reefs and on pilings. It's range is from Nova Scotia to Florida and is a carnivore that prefers barnacles and oysters. It drills a hole into the shell and feeds on the soft parts of the animal.
The New England basket shell, Nassarius trivittatus(Say) is sometimes called a threeline mudsnail, New England Dog Whelk or a New England Nassa is a small shell with a rough surface and strong axial ribbing with beaded whorls. It's between 1/2-7/8" high and is white to yellowish-gray. Southern specimens (as found in North Carolina) have 3 reddish-brown spiral bands on the body whorl. Located on sand and muddy sand and intertidally to water 300 feet deep, it's range is from Canada to Florida. It feeds on egg cases of the Northern Moon Shell and is a scavenger.

Brown-Banded Wentletrap, Variable Dwarf Olive,Florida Auger

Brown-Banded Wentletrap Epitonium rupicola (Kurtz) - This is a beautiful shell. It's between 3/8-1 inch in length and it has a whitish exterior with brown spiral bands. It lives in sounds and just off-shore. It will occasionally wash up on the beach at the tide line. It is a carnivore and forages for the small anemones and secretes a substance that may anesthetize the anemones. It can be found from Cape Cod to Texas, but is more common in northern waters.



This shell is a Variable Dwarf Olive Olivella mutica (Say). It's about 1/2 inch and smooth, shiny and shaped like the larger olive shells. It's creamy white with three reddish brown spiral bands. It's a carnivore and the female lays egg capsules on any hard object found on the sandy bottom, often on empty bivalve or barchiopod shells. It's found from North Carolina to the Bahamas.
I'm not positive about this shell, but according to the Museum of Coastal Carolina on Ocean Isle Beach, NC, it is the Florida Auger, known as the Terebra Floridana (Dall). It's found from NC to Florida in moderately deep water.

Sharp-Knobbed Nassa

This shell is very common on our beaches. It's called a Sharp-knobbed Nassa but other names are sharp-knobbed dog whelk or narrow basket shell. It's a scavenger and is reported to feed on mollusk egg capsules. It's found on the sand from the low-tide line to 20' deep in the water. It's range is NC to Texas. It's scientific name is Nassarius acutus (Say). The size is from 1/4 - 1/2".

Skate egg cases

Here is the picture of the Skate egg cases I was telling you about. They are the egg cases of the clearnose skate (sometimes called a mermaid's purse or devil's purse). It is made of the material which is similar to that of finger-nails. In the sea, these cases will hold the embryos of the skate for several months and then split open to release the fully formed baby skates. From "Florida's Fabulous Seashells And Other Seashore Life" - Williams/Charmichael

Finds on the Beach

Yesterday I came across something neat. It was an old piece of rope, or at least I think it is, and attached to it was a group of about 30 skate egg cases. I've seen one or two or even five attached together but never so many as this find. Needless to say, I dragged it home and put it on the porch to dry along with all the other items drying out (eg: sponges, 4 ghost crabs, a star fish (yes it was dead when I found it) and two large puffer fish (porcupine), one puffed up and the other, not. So, today, I'm going out at high tide to see if I can find more tiny shells ( I've run out of room for any more whelks so I have to look for the minuscule! Happy shelling!

Bruised Nassa,Giant Bittersweet and Lettered Olive

Bruised nassa- Nassarius vibex (Say) is a small shell (about 1/2") with a rough surface. It has a coarsely beaded surface with equal spiral and axial ribs, resulting in about 12 ridges. It has a smooth inner lip with prominent parietal shield. It has a thick and toothed outer lip. It has a grayish brown exterior with a prominent cream-colored shield. It found in shallow-water sand flats on sound and ocean beaches. A scavenger, it also has been observed feeding on eggs of marine worms. (information from "Seashells of North Carolina by Porter and Houser North Carolina Sea Grant College Program")

Giant Bittersweet, Glycymeris americana (DeFrance)

Grows to 4 inches, is round and a somewhat flat shell. Indistinct broad radial ribs sculptured with radiating scratches. It has a central beak and a long curved hinge with 19-24 teeth. It's color is a grayish tan exterior and mottled with yellowish borwn. It lives offshore in depths of 75 feet near and south of the Capefear river. (Information from "Seashells of North Carolina by Porter and Houser - North Carolina Sea Grant College Program")

Lettered olive, Oliva sayana (Ravenel) A smooth, shiny, cylindrical shell with a short spire. Narrow aperture extending almost length of shell, continuing around the bottom and ending in a notch on the other side. No operculum. It's cream or grayish exterior with reddish brown zigzag markings and lives in near-shore waters on shallow sand flats near inlets. It's commonly washed onto ocean beaches. A carnivore, it captures bivalves and small crustaceans with its foot and takes them below the sand surface to digest. Its presence is sometimes detected at very low tides by the trails it leaves when it crawls below the surface on semi-exposed sand flats.

Marsh Periwinkle and Florida Melampus

This is a Marsh Periwinkle, Littorina irrorata.
5/8-1 1/2" (1.6-3.8cm) high. These were found on the high tide line on Ocean Isle Beach, NC. Broadly ovate, think, sharply pointed except when eroded; Whorls smooth, slightly convex. Columellar area and inside of outer lip whitish, the latter with a dark margin and dark brown deep within. Habitat: on rocks intertidally. In Europe, this very common and abundant shell is still gathered and eaten by many people. Information from "The Audubon Society Field Guide to North American Seashells pages 401-2.

The Florida Melampus, Detracia floridana is found at the high tide line. (5/8 ") Small, cone-shaped shell with a short, blunt spire. Long, narrow aperture with front end expanded. Color: Light to dark brown, occasionally with three to four darker-colored spiral bands. Also called a salt-marsh snail, this family has a primitive lung in place of gills and breathes air. The snail eats decaying plant matter but is believed to get its nutrients from the bacteria that live on decaying matter. Information found in"Seashells of North Carolina - NC Sea Grant College Program Porter and Houser".

I received an email from Terri Kirby Hathaway from the NC Sea Grant website and she writes...
Your shells are the eastern mudsnail (/Ilyanassa obsoleta/), very commonin NC estuaries. This animal is also called eastern mud nassa, mud dogwhelk, and the common mudsnail. We find lots of them up here on DareCounty beaches.



"Ilyanassa obsoleta (Say, 1822)

EASTERN MUDSNAIL. COMMON MUD SNAIL, EASTERN MUD WHELK, MUD DOG WHELK, BLACK DOG WHELK, WORN-OUT DOG WHELK, EASTERN MUD NASSA, MUD BASKET SNAIL, OBSOLETE BASKET SNAIL

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Prosobranchia
Order: Neogastropoda
Family: Nassariidae

Ilyanassa obsoleta has a plain, dark black or brown shell, 1.5-3 cm high, with 5-6 whorls (a whorl is one complete turn of the spiral shell) and a blunt, conical spire. The shell's surface is decorated with a network of weak, beaded lines. The aperture (the opening through which the snail emerges) is roughly oval and about half the height of the shell, with a notch at the bottom. The outer rim of the aperture is thin and sharp, and the inner side of the aperture has a spiral fold near its base. The inside surface of the shell is a deep, purplish black. The shell is often covered with mud and algae (and sometimes with the Atlantic bryozoan Alcyonidium polyoum), and in most older snails the tip of the shell is eroded.

Ilyanassa obsoleta is the most abundant intertidal snail on San Francisco Bay mudflats and in the lower reaches of marsh channels, where it is often found in large herds. As this snail crawls over the mud surface it leaves a grooved trail behind, and when the tide goes out it usually burrows under the surface to avoid drying out. It has been collected in the bay in salinities of 10-32 ppt and water temperatures of 13-22° C. It feeds on diatoms and algal detritus that it gleans from the surface layers of the mud, captures and consumes minute worms (in the family Spionidae) that live in the mud, and scavenges on dead fish, crabs and other animal remains. It is fed on in turn by ducks and the larger shorebirds.

Ilyanassa obsoleta deposits its eggs in small, bristly, faceted capsules that are attached to hard surfaces. Each capsule is about 3 mm high and contains several eggs. The capsules are often laid in rows on eelgrass blades, or in rows or clusters on shells, stones or debris on the mudflats. The young snails emerge as free-swimming larvae. The larvae drift in the plankton for 20-30 days, feeding on phytoplankton, before settling to the bottom and metamorphosing into tiny snails. Ilyanassa obsoleta can live for up to 5 years.

The San Francisco Bay mudflats where Ilyanassa obsoleta is now found were once occupied by the native hornsnail Cerithidea californica. Race (1982) describes how each spring the two populations of these snails collide in the lower marsh channels. By mid-summer Ilyanassa obsoleta has restricted the native hornsail to the upper channels and shallow pools in the upper marsh through a combination of egg predation and direct competitive interference. The high marsh pools (also called salt pannes) are too salty for Ilyanassa obsoleta, and thus provide a habitat refuge for the native snail."
from the website: http://www.exoticsguide.org/species_pages/i_obsoleta.html

They also mention that these are not a native species on the west coast and probably came in with a shipment of atlantic clams in the early part of the 20th century.

Shell identification...cont.

They seem to run from16-20mm.

Thanks for your help!

Identification problem

I quit! I've looked at just about all the places google says to go, to find the name of these shells. I think they're periwinkles and I've looked at littoraria, spurwinkia, laemodonta and myosotella and when there were pictures, none of them looked like these banded shells. I sure can use the help. They were found on our crab pot in the canals of Ocean Isle Beach, NC.

I'm new to the more scientific ways of naming what I've found. For the longest time I was happy just finding that beautiful shell. Then came the need to give them a name. Then when I found out there were not only wentletraps, but angulate, Humphreys, frosted, bladed, Champion's wentletraps etc., I knew I was in over my head!