Table 4. A listing of some of the more common phyla of marine animals and the classes that are contained in each of these phyla
| Protozoa | | Mastigophora/flagellates; Sarcodina/amoeboids; Ciliatea/ciliates; Helioza/sun animalcules; Radiolaria | |
| Porifera | | Calcarea/calcareous sponges; Hexactinellida/glass sponges; Demospongiae | |
| Coelenterata | | Hydrozoa/hydroids; Scyphozoa/jellyfishes; Anthozoa/anemones,corals, sea fans | |
| Platy- Helminthes | | Turbellaria/free living flatworms; Trematoda/flukes; Cestoda/tapeworms | |
| Mollusca | | Monoplacophora/Neopalina; Amphineura/chitons; Bivalvia/clams, oysters, mussels, scallops; Scaphopoda/tusk shells; Gastropoda/snail, abalones, nudibranchs, slugs; Cephalopoda/octopi, squid, nautilus | |
| Annelida | | Polychaeta/segmented worms; Oligochaeta/earthworms; Hirudinea/leeches | |
| Arthropoda | | Trilobitomorpha/trilobites; Merostomata; Arachnida/spiders; Pycnogonida/sea spiders; Insecta; Diplopoda/centipedes; Chilopoda/millipedes; Pauropoda; Symphyla; Crustacea/lobsters, shrimps, crabs, barnacles | |
| Echinodermata | | \Stelleroidea/starfish; Ophiuroidea/brittle stars, basket stars; Echinoidea/urchins, sand dollars; Holothuroidea/sea cucumbers; Crinoidea/sea lillies | |
| Chordata | | Urochordata/salps, tunicates; Cephalochordata/acorn worms; Vertebrata/fish, amphibians, reptiles, birds, mammals | |
X. Marine animals.
A. General.
1. More variety than plants, with some phyla exclusively found in the oceans.
2. Invertebrates versus vertebrates, the usual way to break up this multitude of species in the study of zoology.
a. 5% of the animals are vertebrates, the remainder are invertebrates.
b. Artificial categorization of sorts, comparing one subphylum versus the rest of the phylum Chordata and all the other phyla of invertebrates.
c. May make more sense to compare Arthropods versus all else, or even Insects versus non-insects.
d. Reflects the bias of the investigators, but also there is some biological basis for this categorization. The vertebrates represent the most complex (highest evolved?) group of animals so that a study of the simpler versus the complex might be in order.
3. The phyla of animals may be categorized as subphyla by some workers (or even classes by others). There are some phyla that are not listed that may be considered valid by some workers. There are splitters and lumpers in zoologists.
4. The vast diversity is often overwhelming, but all animals must meet the same basic needs for existence.
a. Procurement of food.
b. Procurement of oxygen.
c. Perpetuation of the species, or reproduction.
d. Maintenance of water balance.
e. Removal of metabolic wastes
5. The body structures and physiology of animals reflect their adaptations to meet these
problems of existence, but they are also correlated with:
a. Type of environment.
b. Size of animal.
c. Mode of existence.
6. Marine environment versus the terrestrial:
a. More stable and uniform, with the concentrations of salts and dissolved gases fluctuating
b. Buoyancy provides support, so that the largest IS in the oceans.
invertebrates and vertebrates are all marine forms.
c. Composition of sea water is isotonic to the tissue fluids of most marine animals.
d. Buoyancy and uniformity make sea water an ideal medium for animal reproduction:
1). Eggs can be shed and fertilized in sea water and develop as floating
embryos and larvae with minimal water balance difficulties.
2). Little danger of desiccation, salt imbalance, or of being swept away by
rapid currents, as may be present in rivers.
3). Larvae can be transported by ocean currents to allow for fairly wide
dispersal.
4). Larvae can obtain food for development without a large amount of yolk
in egg.
7. Increase in size leads to surface area to volume ratios decreasing. In small animals, the exchange of gases and wastes are carried out by diffusion and internal transport instead of by organs for excretion.
"Snails without Shells"
Many of us are familiar with snails that have a shell--the ordinary garden snail, moon snails, the black Turban snails, tiny and abundant periwinkles high in the intertidal zone, the pretty tropical black or pink Murex, and wavy-top or turbinid shell. Many of us have also seen, either at underwater film festivals or while diving, sea slugs and/or nudibranchs. These latter mollusks, or soft-bodied animals, are essentially snails that through evolution have either greatly reduced the size of the shell or eliminated the shell entirely in the adult stage of the life cycle.
Although the nudibranchs are most spectacular in their vivid colors, there are a couple of other nearly shell-less snails which are common and readily visible to divers. One is the California Sea Hare, Aplysia californica, which is often misplaced in the genus Tethys. It is a large sea slug, often reaching lengths of nearly 20 inches; the body is brown, or mottled brown, or sometimes almost jet black. It discharges a purplish ink when disturbed. The sea hare is lacking an external shell, but it does have a thin, internal remnant of a shell. The possession of long, ear-like tentacles, which are used to detect odors and chemicals in the water, gives the common name to this sluggish, common mollusk.
The other sea slug commonly seen by many of us sea lovers is the so-called striped sea slug, Navanax inermis. This soft animal is brown, with paler brown bars and bright yellow and iridescent blue spots along the sides of the body. It grows up to 12 .5inches long and is considerably sleeker and less bloated in appearance than the Sea Hare. Unlike the Sea Hare, Navanax is found in the quieter waters of the tidepools and especially abundant in the eel-grass covered mudflats of shallow bays and channels. The interesting feature of this slug is that it is carnivorous on other sea slugs (in fact, it even eats other individuals of its own species, being cannibalistic)! Preliminary work done at Scripps Institution of Oceanography indicates that each Navanax individual secretes a substance and deposits it along its trail on the sand or mud that repels other Navanax individuals. The evolutionary significance of this chemical repellent is not quite clearly worked out yet, but undoubtedly this permits the effective utilization of prey within a given area without the competition or danger afforded by having another hunter in the same area.
Most underwater photographers in southern California rapidly focus on the slow-moving, often graceful and elegant, distinctively-colored nudibranchs (pronounced nude-ee-brank) as subjects for a slide
There are two general groups of nudibranchs: the aeolid group and the dorid animals. These can be differentiated by the pattern of distribution of the cerata. The aeolid ones have these "gills" scattered as a fringe along the sides of the animal, or scattered in several groups along the back, or spread evenly throughout the back; the dorid type has these structures gathered together in a tree-like cluster on the posterior or rear part of the back. There are distinctive family groupings within each type of nudibranch, but for our purposes of identification, the categories of nudibranch--aeolid or dorid type--genus and species or common name should usually suffice.
Nudibranchs are most often found in the quiet waters of tidepools, or at deeper depths. A favorite observation trick for the hardy nudibranch-chaser is that of getting up at 4 a.m. and hitting the tidepools at a minus tide before dawn, especially in the spring months. Of course, many of us divers have taken the easy way out and get up at 9 a.m., go on a dive to Scripps Canyon in the middle of the day, and find these gorgeous creatures in abundance along the vertical walls. These often brightly-colored animals are found creeping along the various attached algal plants on the bottom, feeding on the hydroids (anemone-like creatures) on the blades of the plants, or on sponges encrusting rocky areas. Occasionally, one sees a nudibranch in the water column, swimming by violent convulsive and jerking motions; this is most commonly observed with the abundant purple and orange nudibranch, Flabellina iodinea, commonly called the Spanish Dancer because of this behavior. All nudibranchs are apparently carnivorous, mostly feeding on the hydroids and sponges already mentioned. Thus, in collections made for his scientific categorizations of nudibranchs at Scripps, James Lance takes special care to collect the hydroids or sponges in the immediate area that the nudibranch was found. Jim is the acknowledged world-authority on nudibranchs, especially with the Californian forms. He has an extensive slide collection of over 105 species, and can answer virtually any question one might pose on nudibranchs. He can be contacted at Scripps Institution of Oceanography; undoubtedly, he will invite you along on one of his insane early (pre-dawn) trips to the local tidepools.
The aeolid nudibranchs have been detected with stinging cells in the tips of the cerata. Experiments have demonstrated that these stinging cells are derived from the hydroid food animals as they are present when these hydroids are part of the diet and absent when the hydroids are withheld from the diet. It is obvious that the feeding of these nudibranchs somehow keeps the stinging cells of the hydroids from discharging and these cells pass through the digestive system and migrate out to the ends of the gill-like extensions along the back of the animal. These stinging cells then form a protective mechanism for the nudibranch. What a marvelous evolutionary maneuver to provide protection and food at the same time for these otherwise defenseless creatures!
The conspicuous colors of many of the species actually allow the animals to harmonize well with the colorful background of sea anemones, hydroids, gorgonians, sponges, and plants. Further, although work in this aspect is not definitive, it is thought that many of the species of nudibranchs are distasteful or exude an offensive odor which provides the protection from being eaten by fishes and other predators. Along this line, there is an old published record of a Professor Herdman who experimented with various species and found that several of the larger species were left alone by fishes. He thus decided to test their palatability and ate a live specimen of a conspicuous species, Ancula cristata; he reported that "...the taste was pleasant, distinctly like that of an oyster..." Interviews with hundreds of divers and other seafood and seashore lovers offer no other opinion--no one else seems to have tasted a nudibranch!
Lest you fear that this article is going to end without identifying some of the more common and conspicuous nudibranchs other than those already discussed, be assured that your fear has proven to be real. The verbal and written description of these colorful and camera-ready models of sea animals cannot do justice to them; rather, should you have a particular species you need identified, your best bet is to contact Jim Lance at Scripps or to find a color plate of the animal in Behrend's 1980 paperback called Pacific Coast Nudibranchs. Of course, you can always fall back on the least desirable method--i.e., by contacting me. I would have to go through books or call Jim myself, and I believe that you can gain precious time and mountains more information by working directly with those contacts yourself.
Wouldn't it be exciting some evening, especially those wintry days in San Diego when the heavens pour out their leaky aquariums, to sit around a nice fire and watch slides of 40-50 different species of local nudibranchs? Try the Underwater Photographic Society (272-1120 for more information), and you might be able to entice an artist like Fred Fischer or Dave Slidders to come and present such a show. Perhaps a nice lobster dinner or tender steak as an inducement would insure their presence. Or, better yet, how about your own slide show, presenting it to your favorite person(s) and inviting me for the lobster dinner!!!.
VIII. Photosynthesis and marine plants.
A. Photosynthetic reaction is an endothermic one, in which the energy derived from solar/light is
1. 6 co2 + 6 h2o c6h1206 + 6 o2
2. Absorption of photon (quantity of light) is accomplished by the universal pigment
found in all green plants, chlorophyll alpha.
4. Dark (or enzymatic) reaction: co2 ch2o
5. This ch2o is the general organic material used as food by plants and animals.
B. The effect of light on photosynthesis (ps).
1. Intensity:
to a point. During this phase, it is temperature independent, as the ps is going on as fast as the enzymatic reaction allows.
a. There is a maximum rate of ps that is reached, which is called saturation,
where the rate is constant with increasing light intensity. The actual saturation level reached is dependent on:
1). Temperature: at a certain temperature, the photochemical reaction is
going on as fast as the enzymatic reaction, which is temperature dependent, allows it to go on.
2). The optimum point or saturation level is dependent also on genetics or environmental history.
b. There is a solarization point, beyond which any further increase in light
Intensity yields a decrease in the rate of ps.
d. Plants are adapted to certain light intensities:
1). Shade plants--those that are injured by high light intensities.
2). Sun plants--those that display optimal growth at high light intensities.
2. Quality of light:
a. Light needs to be absorbed to become available for ps.
b. Plants have a variety of pigments, but all photosynthetic green plants have one
common pigment, chlorophyll alpha.
c. Dinoflagellates, diatoms, brown algae, red algae, and blue-green algae have
other pigments that may mask the green coloration of chlorophyll.
d. What is the role of these accessory pigments?
1). Cut down excessive light, as in the case of the many brown and red
algae that live in the intertidal areas. Too much light there for these plants so that the accessory pigments act as screens to filter out excessive light.
2). Absorption of light that is available at depth that is not able to be
absorbed by chlorophyll alpha for photosynthesis. Experiments and measurements demonstrate that the light that is absorbed by these pigments become active in ps, since the absorption spectrum and action (ps) spectrum of diatoms, dinoflagellates, phaeophytes, and blue-green algae are all closely related.
IX. Production in the sea.
A. Respiration (r).
1. Generalized reaction is the opposite of ps, with the oxidation of organic matter
resulting in the release of carbon dioxide and water.
2. All living organisms respire, including plants, so that in order for a plant to grow, ps
must be greater than r for that plant.
3. The compensation point is that point at which ps = r ; thus, the compensation depth
is that depth at which the production of oxygen by photosynthesis is offset by the utilization of oxygen by organisms.
4. There is an effect due to temperature: if a plant is growing at 30 meters of depth in 500
C. water, and is then placed in 100 C. water at the same depth, it will respire more and thus show a lesser growth since it will respire more but not necessarily photosynthesize more.
B. Conditions of growth for marine plants:
1. Suitable physical conditions in the environment:
a. Temperature range.
1). Cold-adapted forms, such as the arctic dinoflagellates that display
optimum growth at 5-10 degrees centigrade (40-50 degrees Fahrenheit).
2). Heat-adapted forms, such as some of the
optimize growth in 50-60 degrees C. (120-140 degrees F).
3). As you might expect, most are in the range of 15-35 degrees C. (60-95
degrees F.) which is the temperature range found in most of the oceans.
b. Suitable light conditions.
c. Suitable pH conditions.
d. Suitable substrate.
e. Suitable salinities.
f. Suitable salt balance, such as the sodium/calcium ratio being 98/2.
g. Suitable nutrient medium.
1). Specific elements necessary for growth for all marine plants, in that no
other elements can be substituted.
a). Macronutrients, are those that are major element requirements
for all, such as carbon, hydrogen, oxygen, magnesium (chlorophyll), potassium, phosphorus, and nitrogen (pretty much the stuff that you see in the makeup of commercial fertilizers).
b). Micronutrients, are those that are needed by all in
microquantities, or in trace amounts, such as iron, calcium, zinc, manganese, and copper. All of these are essential in the construction and action of enzymes.
2). Specific elements necessary for growth of some marine algae but not
all:
a). Silicon--diatoms, for the construction of frustules.
b). Sodium--blue-green algae, in phycocyanin.
c). Molybdenum--trace element in many algae.
3). In the oceans, the critical determinants of plant productivity are
phosphorus, nitrogen, and iron (pretty much the same as for the land plants, as is well known by those of you who garden).
4). Accessory growth factors, such as vitamin b12.
C. Primary productivity:
1. Definition: the amount of organic matter that is synthesized from inorganic carbon
through photosynthesis per unit volume/unit sea surface per unit time. usually given as mg. c fixed/square meter or cubic meter per year. Refers to the amount of plant production that goes on within an area for a given unit of time.
2. How does one measure primary productivity?
a. One simple estimate is by "counting" the standing crop , which is the amount of living plant (or animal if measuring biomass instead of primary productivity) material at a given time within a given space. This can be done in several ways:
1). Straight counting, using sophisticated equipment such as the
untermohl inverted microscope. Rather than take the entire sample of a lot of water, take only a certain portion (aliquot) of the entire volume and extrapolate the estimate based on the counts from the aliquot. For reliability, generally take more than one aliquot and average out the counts. The sample taken must be one that is selected randomly, rather than one that the "counter" selects.
2). Filtration--use filters of pore sizes less than 1 micron and filter a
known volume of sea water, then use a high-power microscope to count the plants in the filtrate.
3). Pigment determinations.
4). In any system, the method used to get the original sample is critical,
especially since the phytoplankton is often patchy and consists of different sizes.
a). Microplankton, commonly called the net plankton, with sizes
greater than 70 microns in diameter (standard mesh size of plankton nets).
b). Nannoplankton--5 to 70 microns in diameter.
c). Ultraplankton--less than 5 microns in diameter.
d). Whereas older investigations have indicated the major role in
productivity enjoyed by diatoms and dinoflagellates, using the standard plankton tows for sampling, recent studies have shown that there were no stations where net plankton was more than 80% of the total, and it frequently composed as low as 2% of the total. The average is between 10-12% of the total. It appears that nannoplankton is much more effective in photosynthesis than net plankton per unit volume.
e). Work in the tropics have demonstrated that coccolithophores,
ranging in sizes from 3-20 microns, are one of the more important producers in warm waters.
f). However, in temperate and higher latitudes, where primary
productivity is the highest, diatoms are definitely the most important producers in oceans.
g). As one journeys from the higher latitudes to lower ones, or
from the polar regions to the tropics, total number of species in phytoplankton increases but dominance by any few species decreases.
5). Variability in standing crop over time and space makes standing crop
not a very good measure of primary productivity.
a). Scripps pier, counting Nitzchia seriata, a diatom: (1). on January 29, 16 samples, less than 5 cells per liter in
6 of them.
(2). on January 30, 16 samples, 200 cells per liter at 0800
hours and 2000 cells per liter at 2000 hours.
(3). on January 31, 16 samples, 10,000 cells per liter.
b). In the
with 0-1 cells/liter, 25,000 cells/liter, 100,000 cells/l., and 500,000 cells/l.
c). Allen noted that, on a yearly basis, variability ranged from
112,000 cells per liter to 2000 cells per liter (in
6). Pigment distributions: chlorophyll alpha ranged from 0.01 mg per
cubic meters to 0.10 mg per cubic meters in tropical waters and up to 10-75 mg per cubic meters in northern waters.
b. Equation for Ps is carbon dioxide + water yielding plant material + oxygen; thus, one can use carbon dioxide utilization, carbohydrate production, or oxygen production to measure productivity. Can also use ph differences or nutrient uptakes.
1). Oxygen uptake--3 bottle scheme. This was the method used in
oceanography for a long time, up to the use of radioactive carbon counters.
a). Aliquot sample into 3 bottles. Measure the amount of oxygen
in first bottle, to give a measure of how much oxygen there is at the start.
b). Place bottle 2 in dark conditions for a given amount of time,
and
c). Place bottle 3 in light conditions for the same amount of time.
d). In bottle 2 in the dark, the plants are not photosynthesizing,
only respiring, so that the amount of oxygen should end up less than that measured in bottle 1. The difference (oxygen in bottle 1 minus that in bottle 2) represents the amount of oxygen used up by the plants in respiration over the time units.
e). In bottle 3 in the light, the plants are actively
photosynthesizing, so that the amount of oxygen should be greater than that in bottle 1. However the difference between them (oxygen in bottle 3 minus that in bottle 1) is not the total amount of oxygen produced by photosynthesis, but only amount of oxygen in excess of respiration.
f). Therefore, in order to get the total amount of oxygen produced
by photosynthesis, need to add the respiration (bottle 1 minus 2) and excess (bottle 3 minus 1).
2). Carbohydrate production not feasible because net changes are usually
too minute to measure accurately. Ditto for ph changes and carbon dioxide utilization.
3). Radioactive carbon tagging methods: c14 is introduced into the water
in the form of sodium carbonate. After a period of time, measure the amount of carbon 14 taken up into the organisms. Very sensitive, can detect very small changes. Method most commonly used now.
3. Land productivity has been estimated at 2 x 1010 tons of carbon fixed per year, while
that of the oceans has been estimated at 2 x 10 11 tons of carbon fixed annually, This means that the oceans produce 10 times as much plant productivity as the land masses.
a. Bladder form, as in Coscinodiscus, a diatom, or Noctiluca, a dinoflagellate.
b. Ribbon form, as in Eucampia, a diatom, or the several species of dinoflagellates that link together into chains.
3. Reduction in streamlining: exposing more surface area to the axis of sinking, or travel
along a longer route of sinking due to the body shapes.
a. Filamentous, as in the diatom, Rhizosolenia.
vii. Adaptations of Marine Plants.
A. General.
1. Less than 2% of the substrate in the oceans is available for attachment for
marine
2. Photosynthetic zones in the oceans :
b. Dysphotic zone: where there is light present to carry out
photosynthesis, but not very well. The production of oxygen by photosynthesis is less than that taken up by respiration. This is that layer in the oceans below the euphotic zone and down to depths of no greater than 200 meters.
a. Sargassum of the
neverproduces reproductive organs while floating in the
b. All phytoplankton are unicellular, although some form colonial chains
in which the individual one-celled plants are attached to each other.
c. Must mean that small plants have some advantage over large plants as
phytoplankton. d. Specific gravities:
1). Sea water = 1.02575
2). Protoplasm = 1.02 to 1.06
Now, for the Harbor Seal:
Harbor seals are found in temperate, subarctic, and arctic waters of the
Male harbor seals get up to 6 feet long, with weights up to 375 pounds, although most are a bit smaller. Females are smaller, at 5.5 feet long and weights to 330 pounds. They have a rounded, fusiform body, much “chubbier” than the sea lions.
The harbor seals range in color from light gray to silver with dark spots. Some are black or dark gray to brown with white rings.
The limbs are modified into flippers, as with the sea lions. A harbor seal’s foreflippers are short and webbed, unlike the elongated ones of the sea lions. They also contain noticeable claws, unlike those of the sea lions. The harbor seals use the claws for scratching, grooming, and defense. The foreflippers are covered with hair, absent in the sea lions. There are claws and hair on the hind flippers as well. The harbor seals use their hind flippers in a side to side motion to propel themselves through the water, using them as rudders as well. However, on land, they cannot rotate the hind flippers under the body, so that it moves by bouncing in a caterpillar like motion.
The harbor seal has a rounded head with a fairly blunt snout. It lacks external ear flaps, which we can easily see in sea lions. The teeth are similar to those of the sea lions, used mainly for grasping and tearing but not for chewing. The whiskers/vibrissae are located around the upper lip and cheeks.
In all of its senses (hearing, eyesight, touch, and smell), the harbor seals are similar to the sea lions. As with sea lions, it is believed that their taste sense is weak or nonexistent.
The swimming of harbor seals, although different from sea lions in the use of the hindflippers for propulsion instead of the foreflippers, is otherwise similar in that speeds are around 12 mph, but generally cruising at slower speeds.
They live in shallow waters, and hence, they normally do not dive deep, but it is known that they can dive to more than 600 feet. They can stay submerged for up to 30 minutes, but dives usually last no longer than about 3 minutes. The same physiological adaptations for diving occurs in the harbor seal as in the sea lion.
In fact, much of the physiology and biology of the harbor seal mimics those of the sea lion. However, their behavior is different, in that they are usually solitary and rarely interact with each other except for mating. They will haul out (term used to describe the action of seals/sea lions coming out of the water to inhabit a beach) in loosely organized groups (such as the one at Casa Cove in
Since they cannot rotate their hind flippers under their bodies, their haul out places are limited by height and by tides.
They are probably the least vocal of all pinnipeds. They may snort, hiss, growl, or sneeze in air, although their vocalizations are mainly underwater.
They compete with the sea lions for the same/similar food in the same areas. They eat about 5-6% of the body weight daily (10-18 pounds).
The reproductive actions and process is similar to those of the sea lions except that the males do not maintain as large “harems” nor territories. The pups nurse only for 4-6 weeks, instead of the much longer 6-8 months for the sea lions.
The longevity of harbor seals is about the same as that for sea lions, and human interaction is one of the chief causes for concern for their health in the oceans.
