1. singer does reject speceisism. i am a bit softer than him on that
point, but i tend to agree overall.
2. this does not compel one to starve to death, unless one believes that
all moral rules/positions are absolute. which is rarely the case.
3. from (2), there is no clean line that is drawn in the living world on
who "deserves" respect/life and who does not. again, such a
conclusion is necessary only if the particular moral rule (governing
what you rule) is given precedence over others.
w.r.t formal terms:
the fundamental question is: do we have a need for ethical rules or morality? if you believe not, we need to restart this conversation. assuming you do:
it seems to me, we can derive moral rules in a few different ways. we can proceed from self-interest (assuming that every _human_ axiomatically maximizes his/her interest, especially survival) and arrive at arrangements that maximize everyone's interest (perhaps what economists call pareto optimality?). one can argue that the complexity of this venture defies completeness or even arriving at broad and useful results. or one can alternately insist that evolutionary and cultural history demonstrates that some of the ethical rules we currently use, do indeed address this issue.
consider the situation where you have limited medication and you have to provide it to temporarily prolong the life of a person who is comatose with no chances of recovery (i was hoping to avoid a segue into disability rights, but perhaps it is appropriate and may educate me on the matter), or that of a person fully conscious but terminally ill. whom do you provide the medication to? to make it even easier, what if the second person could miraculously be cured by the medication?
these are _practical_ problems, yes? what are the rules we use, in the public sphere, to solve these problems?
i guess for libertarians and other conservative types, the rule would be something like 'well, whomever can afford it, gets it', or some derivation of it.
if, like singer, you are a utilitarian, or you are a particular type of humanist (or even leftist), you may use other rules. perhaps you may say that since we value both life and consciousness (the conscious living and experiencing of life) we would provide the medicine to the ill but conscious person.
singer's point is that if you were to apply such a set of rules consistently, then you would be obliged to oppose experiments on primates, and from there all the way to consumption of animals when alternatives are available.
of course ethics and morality are human concepts. the point though is not an anthropomorphic transference of such modes to animals, but a consistent application of them. per singer, the additional [meta] rule, that moral/ethical rules (and the reasoning behind them) should be "arbitrarily" terminated at the human boundary, is speceisism.
i do not imply that his position is airtight (though, like luke, i think he is fairly consistent and even right). as i pointed out there are some philosophical critiques of singer, especially his utilitarianism (and his derivation of his animal ethics from it).
here is a decent (but incomplete) summary of some of the issues of interest:
http://www.humboldt.edu/~essays/v5n2intro.html
--ravi