Many Miami environmental science graduate students take the Ecology Field Courses each year.
Starfish are found in the animal phylum, Echinodermata. Echino comes from the Greek word spiny and derma meaning skin. There has been six classes that fall under this phylum: Class Concentricycloidea, Class Holothurodea, Class Crinoidea, Class Echinoidea, Class Asteroida, and Class Ophiuroidea. The two classes that you will find the starfish are Asteroida (Sea Star) and Ophiuroidea (Brittle Star). The Brittle Star has a distinct boundary between the arm and central disk where the Sea Star has the arms connected to one another. We better know Sea Stars, and more likely what we will encounter.
“The Echinoderms possess three unique and distinctive features: a body plan with five-part symmetry, an internal calcite skeleton, and a water-vascular system of fluid-filled vessels that are manifested externally as structures called tube feet,” (Hendler, Kier, Miller, and Pawson, 18).
The first process becoming a starfish starts out like humans, with reproduction. With the starfish, fertilization is external. The female Starfish sheds several million eggs and are released into the water. After the eggs match up with sperm, a hallow ball (called the blastula) develops. After the fertalization process, the embryo turns into the blastula to the larva to a miniature starfish. The process takes about two months. The starfish is a juvenile up until six months of age. They start with three or four arms and develop more later on. After the age of six months, the starfish is mature.
The body of the starfish consists of many parts. The starfish has no ears, nose, or eyes. There is basic central disk and symmetrical arms (rays). The rays typically come in the number five, although some have up to fifty (Hendler, Kier, Miller, and Pawson, 60). The Major anatomical features located on the upper portion of the starfish are: the arm, anus, madreporite, papulae, and ocular plate. Located underneath the starfish are the mouth, jaw, arm furrow, and tube feet. The starfish has a water vascular system. The tube feet are the primary site of oxygen uptake. (Lawrence, 131). Canals are connected to the tube feet, which connect to the disk.
The diet of the starfish starts with encrusting algae as a juvenile. The diet changes as they grow. The can eat shelled animals such as: Oysters, clams, sea urchins, barnacles, mussels, and other small animals. Some starfish even eat other starfish. The eating process is interesting. The starfish sneaks up and jumps on the food and surrounds the shell. It uses suction to pull apart he shell and puts its stomach into the shell to eat the inside. The stomach moves back into the starfish when it is done.
Within the better well-known class, Asteroida, of starfish, there are approximately 1,800 living species (Hendler, Kier, Miller, and Pawson, 18). While there are to many to discuss, and ones we will not see, I have narrowed it down to a few from different families, to discuss ones we may see in the Bahamas as well as the Florida Keys. These species can be found in numerous other places, but I will only mention the places we are going.
Luidia clathrata, family Luidiidae, can be found in the Florida Keys. Its habitat is in "protected inshore areas such as lagoons and bays on sand or mud sediments; offshore on sand and shell hash," (Hendler, Kier, Miller, and Pawson, 68). To feed, avoid light, and to protect itself, it burrows into the sand. We will be able to see the dead bodies after a storm hits. Thousands of their bodies will wash up on shore. These sea stars have a small disk and five long, flat, strap like arms. The larger of the Luidia clathrata are 8-11 inches in diameter. On each arm to the disk, there is a black or gray stripe. There are no suckers on the tube feet; they are pointed. They can be found around a depth of 131 feet. (Hendler, Kier, Miller, and Pawson, 68-69).
Astropecten articulatus, family astropectinidae, can be found in the Bahamas as well
as the Florida Keys. Its habitat is in "soft sediment composed of sand or shell hash," Hendler, Kier, Miller, and Pawson, 73). The moderate-sized adults can reach to be 8 inches. They have five flat arms and are two to three times greater in length to the disk diameter. Their color is a drab gray or light brown. Some have light brown on the central portion of the arms and disk. The marginal plates are mottled with dark reddish brown to a light pink. They can be found around a depth of 24-42 feet. (Hendler, Kier, Miller, and Pawson, 72-74).
Asterina folium, family asterinidea, can be found in the Bahama Islands and Florida
Keys. Its habitat is in "Coral reefs, particularly on the reef flat, and spur-and-groove zones, usually under coral rubble or rock, or in the reef framework," (Hendler, Kier, Miller, and Pawson, 74). This sea star is a small species of 1 inch in its whole diameter. It has short, bluntly rounded arms and is pentagonal shaped. The dorsal surface is covered in scales. They are mostly white. The Intermediate sized ones are yellow or yellowish red. The larges are blue to blue-green. They can be found in the low-tide mark of 49 feet. (Hendler, Kier, Miller, and Pawson, 74-75).
Linckia guildingii, family Ophidiasteridae, can be found in the Bahamas Islands and
Florida. Its habitat is "Usually on coral reef hard bottom; also reported from sandy beds between reefs," (Hendler, Kier, Miller, and Pawson, 78). This species has a small disk and slender arms, mostly of unequal length. They can have anywhere from 4 to 7 arms. The longest of the arms is between 9-10 times the diameter of the disk. Small swollen plates cover the smooth granules of the upper surface of the arms. juvenile are shades of red, brown, violet, or purple. Adults are reddish brown, yellowish brown, tan or violet. They can be found at a depth usually less than 3 to 6 feet. (Hendler, Kier, Miller, and Pawson, 77-78).
Poraniella echinulata, family Asteropseidae, can be found in the Bahamas Islands and
in Florida. Its habitat is "on hard substrates, beneath coral rubble and rock in shallow reef habitats, (Hendler, Kier, Miller, and Pawson, 82). This species of sea star is one of the smallest in tropical western Atlantic. It is usually less than 1 inch in diameter. It has a broad disk and five short arms, which are wide, flat, and thin. They are covered with thick, fleshy tissue. The upper surface is bright orange-red to a blood red color. It is variegated with white. Some have white pigment that forms a pentagon in the center of the disk. There is also a distinctive stripe along the arms midline. There is a mottled black and white color on the tips of the arms. The fleshy papulae are pale orange and the madreporite is a light tan color. The tube feet are transparent with no color. The under surface is orange-red but with white tips on the jaws' tips. They have been found around a depth of 492 feet. (Hendler, Kier, Miller and Pawson, 81-82).
Oreaster reticulatus, family Oreasteridae, can be found in Florida and the Bahamas
Islands. Its habitat is in "shallow, quiet waters of reef flats, lagoons, and mangrove channels," (Hendler, Kier, Miller and Pawson, 83). It is one of the most widely known sea stars in the Caribbean. It can reach a diameter of 20 inches. It has a massive disk that is inflated with five short tapering arms. The top surface has thick, heavy plates. The bottom surface is flat with a shallow concavity near its mouth. The top surface of a juvenile is usually a mottlet green, tan, brown, and gray. The top surface of adults is yellow, orange, or brown. The erect tubercles are lighter or darker than the disk and arms. Both adult and juvenile have a bottom surface of cream or beige. On a calm, clear day, there is a chance to see them in grass beads or sand patches. They can be found at a depth of 3 to 120 feet. (Hendler, Kier, Miller and Pawson, 82-84).
The last sea star is the Echinaster echinophours, family Echinasteridae. It can be found in the Florida Keys. Usually found in shallow water. Its habitat is "usually associated with hard subtrates," (Hendler, Kier, Miller and Pawson, 84). This small species has a diameter of 2.8 inches. It has a small disk and five arms. The arms taper slightly and flattened ventrally. They have widely spaced plates and are covered with thin skin. The tip surface has thorn like, erect spines. There are 6 to 9 spines on each row measuring to a length of 0.08 to 0.12 inches. The sides of the arms have a straight row of spines. The bottom surface has grooves outlined by three series of spines. Their color is red or crimson. The can be found at a depth of 180 feet. (Hendler, Kier, Miller and Pawson, 84-85).
These are just seven different sea stars. Starfish are an important factor in marine life. A great decline of the starfish would affect the life of other systems in the ocean. They are beautiful animals. I hope to learn more about them as we explore the Florida Keys and the Bahamas.
Bavendam, Fred. Beneath Cold Waters: The Marine Life of New England. Down Eawst Books. Camden, ME. 1980.
Hendler, Gordan and Kier, Porter M. and Miller, John E. and Pawson, David L. Sea
Stars, Sea Urchins, and Allies. Smithsonian Institution. 1995.
Lawrence, John. The Functional Biology of Echinoderms. The Johns Hopkins
University Press: Baltimore, MD. 1987.
Prayer of the Starfish
The depths have closed over me.
Am I not
fallen from heaven
to the torments of the waves?
I look like a blood star.
I try to remember
my distant royalty
but in vain.
Crawling on the sand,
I open my arms
and I dream, I dream, I dream…
could not an angel
pull me up
from the bottom of the sea
to place me again
in Your heaven?
Ah! One day,
So be it!
Translated by John Lawrence
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